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[PATCH v6 0/22] On-demand device probing

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  [PATCH v6 0/22] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 14/22] usb: phy: Probe phy devices on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 09/22] drm: Probe panels on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 12/22] pwm: Probe PWM chip devices on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 01/22] driver core: handle -EPROBE_DEFER from bus_type.match() Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 15/22] clk: Probe clk providers on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 19/22] power-supply: Probe power supplies on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 20/22] driver core: Allow deferring probes until late init Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 16/22] pinctrl: Probe pinctrl devices on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 17/22] phy: core: Probe phy providers on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 21/22] driver core: Start processing deferred probes earlier Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:10 +0200
    [PATCH v6 07/22] regulator: core: Remove regulator_list Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200
      Re: [PATCH v6 07/22] regulator: core: Remove regulator_list Mark Brown <broonie@kernel.org> - 2015-09-21 21:40 +0200
        Re: [PATCH v6 07/22] regulator: core: Remove regulator_list Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-22 09:30 +0200
    [PATCH v6 02/22] ARM: amba: Move reading of periphid to amba_match() Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200
    [PATCH v6 04/22] of: add function to allow probing a device from a OF node Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200
    [PATCH v6 05/22] gpio: Probe GPIO drivers on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200
    [PATCH v6 11/22] i2c: core: Probe i2c adapters and devices on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200
    [PATCH v6 06/22] gpio: Probe pinctrl devices on demand Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-09-21 16:20 +0200

#1229390 — [PATCH v6 0/22] On-demand device probing

Hello,

I have a problem with the panel on my Tegra Chromebook taking longer
than expected to be ready during boot (Stéphane Marchesin reported what
is basically the same issue in [0]), and have looked into ordered
probing as a better way of solving this than moving nodes around in the
DT or playing with initcall levels and linking order.

While reading the thread [1] that Alexander Holler started with his
series to make probing order deterministic, it occurred to me that it
should be possible to achieve the same by probing devices as they are
referenced by other devices.

This basically reuses the information that is already implicit in the
probe() implementations, saving us from refactoring existing drivers or
adding information to DTBs.

During review of v1 of this series Linus Walleij suggested that it
should be the device driver core to make sure that dependencies are
ready before probing a device. I gave this idea a try [2] but Mark Brown
pointed out to the logic duplication between the resource acquisition
and dependency discovery code paths (though I think it's fairly minor).

To address that code duplication I experimented with Arnd's devm_probe
[3] concept of having drivers declare their dependencies instead of
acquiring them during probe, and while it worked [4], I don't think we
end up winning anything when compared to just probing devices on-demand
from resource getters.

One remaining objection is to the "sprinkling" of calls to
of_device_probe() in the resource getters of each subsystem, but I think
it's the right thing to do given that the storage of resources is
currently subsystem-specific.

We could avoid the above by moving resource storage into the core, but I
don't think there's a compelling case for that.

I have tested this on boards with Tegra, iMX.6, Exynos, Rockchip and
OMAP SoCs, and these patches were enough to eliminate all the deferred
probes (except one in PandaBoard because omap_dma_system doesn't have a
firmware node as of yet).

Have submitted a branch [5][6][7] with these patches on top of today's
linux-next (20150921) to kernelci.org and I don't see any issues that
could be caused by them.

With this series I get the kernel to output to the panel in 0.5s,
instead of 2.8s.

Regards,

Tomeu

[0] http://lists.freedesktop.org/archives/dri-devel/2014-August/066527.html

[1] https://lkml.org/lkml/2014/5/12/452

[2] https://lkml.org/lkml/2015/6/17/305

[3] http://article.gmane.org/gmane.linux.ports.arm.kernel/277689

[4] https://lkml.org/lkml/2015/7/21/441a

[5] https://git.collabora.com/cgit/user/tomeu/linux.git/log/?h=on-demand-probes-v8

[6] http://kernelci.org/boot/all/job/collabora/kernel/v4.3-rc2-2587-gf92b0ab33d14/

[7] http://kernelci.org/boot/all/job/next/kernel/next-20150921

Changes in v6:
- Drop bus_type.pre_probe and read the periphid in match() instead as
  suggested by Alan Stern.
- Merge changes to the regulator subsystem's locking so no references
  are leaked between commits.

Changes in v5:
- Set the pointer to struct device also for AMBA devices
- Unset the pointer to struct device when the platform device is about
  to be unregistered
- Increase the reference count of the device before returning from
  of_find_device_by_node()
- Move the assignment to device_node->device for AMBA devices to another
  commit.
- Hold a reference to the struct device while it's in use in
  of_device_probe().
- Use regulator_class' klist of devices instead of regulator_list to
  store and lookup regulator devices.

Changes in v4:
- Added bus.pre_probe callback so the probes of Primecell devices can be
  deferred if their device IDs cannot be yet read because of the clock
  driver not having probed when they are registered. Maybe this goes
  overboard and the matching information should be in the DT if there is
  one.
- Rename of_platform_probe to of_device_probe
- Use device_node.device instead of device_node.platform_dev
- Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in
  machines with initcalls that depend on devices probing at a given time.
- Start processing deferred probes in device_initcall_sync
- Also defer probes of AMBA devices registered from the DT as they can
  also request resources.

Changes in v3:
- Set and use device_node.platform_dev instead of reversing the logic to
  find the platform device that encloses a device node.
- Drop the fwnode API to probe firmware nodes and add OF-only API for
  now. I think this same scheme could be used for machines with ACPI,
  but I haven't been able to find one that had to defer its probes because
  of the device probe order.

Tomeu Vizoso (22):
  driver core: handle -EPROBE_DEFER from bus_type.match()
  ARM: amba: Move reading of periphid to amba_match()
  of/platform: Point to struct device from device node
  of: add function to allow probing a device from a OF node
  gpio: Probe GPIO drivers on demand
  gpio: Probe pinctrl devices on demand
  regulator: core: Remove regulator_list
  regulator: core: Probe regulators on demand
  drm: Probe panels on demand
  drm/tegra: Probe dpaux devices on demand
  i2c: core: Probe i2c adapters and devices on demand
  pwm: Probe PWM chip devices on demand
  backlight: Probe backlight devices on demand
  usb: phy: Probe phy devices on demand
  clk: Probe clk providers on demand
  pinctrl: Probe pinctrl devices on demand
  phy: core: Probe phy providers on demand
  dma: of: Probe DMA controllers on demand
  power-supply: Probe power supplies on demand
  driver core: Allow deferring probes until late init
  driver core: Start processing deferred probes earlier
  of/platform: Defer probes of registered devices

 drivers/amba/bus.c                  |  88 ++++++------
 drivers/base/Kconfig                |  18 +++
 drivers/base/dd.c                   |  35 ++++-
 drivers/clk/clk.c                   |   3 +
 drivers/dma/of-dma.c                |   3 +
 drivers/gpio/gpiolib-of.c           |   5 +
 drivers/gpu/drm/drm_panel.c         |   3 +
 drivers/gpu/drm/tegra/dpaux.c       |   3 +
 drivers/i2c/i2c-core.c              |   4 +
 drivers/of/device.c                 |  61 +++++++++
 drivers/of/platform.c               |  30 +++--
 drivers/phy/phy-core.c              |   3 +
 drivers/pinctrl/devicetree.c        |   3 +
 drivers/power/power_supply_core.c   |   3 +
 drivers/pwm/core.c                  |   3 +
 drivers/regulator/core.c            | 257 +++++++++++++++++++++++-------------
 drivers/usb/phy/phy.c               |   3 +
 drivers/video/backlight/backlight.c |   3 +
 include/linux/device.h              |   4 +-
 include/linux/of.h                  |   1 +
 include/linux/of_device.h           |   3 +
 21 files changed, 386 insertions(+), 150 deletions(-)

-- 
2.4.3

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#1229392 — [PATCH v6 14/22] usb: phy: Probe phy devices on demand

When looking up a phy through its OF node, probe it if it hasn't
already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/usb/phy/phy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/phy/phy.c b/drivers/usb/phy/phy.c
index 98f75d2842b7..fb0b650bb494 100644
--- a/drivers/usb/phy/phy.c
+++ b/drivers/usb/phy/phy.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 
 #include <linux/usb/phy.h>
 
@@ -196,6 +197,8 @@ struct  usb_phy *devm_usb_get_phy_by_node(struct device *dev,
 		goto err0;
 	}
 
+	of_device_probe(node);
+
 	spin_lock_irqsave(&phy_lock, flags);
 
 	phy = __of_usb_find_phy(node);
-- 
2.4.3

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#1229395 — [PATCH v6 09/22] drm: Probe panels on demand

When looking up a panel through its OF node, probe it if it hasn't
already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/gpu/drm/drm_panel.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 2ef988e037b7..ad79a7b9c74d 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -23,6 +23,7 @@
 
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/of_device.h>
 
 #include <drm/drm_crtc.h>
 #include <drm/drm_panel.h>
@@ -80,6 +81,8 @@ struct drm_panel *of_drm_find_panel(struct device_node *np)
 {
 	struct drm_panel *panel;
 
+	of_device_probe(np);
+
 	mutex_lock(&panel_lock);
 
 	list_for_each_entry(panel, &panel_list, list) {
-- 
2.4.3

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#1229396 — [PATCH v6 12/22] pwm: Probe PWM chip devices on demand

When looking up a PWM chip through its OF node, probe it if it hasn't
already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/pwm/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 3f9df3ea3350..794a923df0d8 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -29,6 +29,7 @@
 #include <linux/device.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/of_device.h>
 
 #include <dt-bindings/pwm/pwm.h>
 
@@ -516,6 +517,8 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
 {
 	struct pwm_chip *chip;
 
+	of_device_probe(np);
+
 	mutex_lock(&pwm_lock);
 
 	list_for_each_entry(chip, &pwm_chips, list)
-- 
2.4.3

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#1229397 — [PATCH v6 01/22] driver core: handle -EPROBE_DEFER from bus_type.match()

Lets implementations of the match() callback in struct bus_type to
return errors and if it's -EPROBE_DEFER then queue the device for
deferred probing.

This is useful to buses such as AMBA in which devices are registered
before their matching information can be retrieved from the HW
(typically because a clock driver hasn't probed yet).

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/base/dd.c      | 24 ++++++++++++++++++++++--
 include/linux/device.h |  2 +-
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index be0eb4639128..7dc04ee81c8b 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -488,6 +488,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 	struct device_attach_data *data = _data;
 	struct device *dev = data->dev;
 	bool async_allowed;
+	int ret;
 
 	/*
 	 * Check if device has already been claimed. This may
@@ -498,8 +499,17 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
 	if (dev->driver)
 		return -EBUSY;
 
-	if (!driver_match_device(drv, dev))
+	ret = driver_match_device(drv, dev);
+	if (!ret)
 		return 0;
+	else if (ret < 0) {
+		if (ret == -EPROBE_DEFER) {
+			dev_dbg(dev, "Device match requests probe deferral\n");
+			driver_deferred_probe_add(dev);
+		} else
+			dev_warn(dev, "Bus failed to match device: %d", ret);
+		return ret;
+	}
 
 	async_allowed = driver_allows_async_probing(drv);
 
@@ -619,6 +629,7 @@ void device_initial_probe(struct device *dev)
 static int __driver_attach(struct device *dev, void *data)
 {
 	struct device_driver *drv = data;
+	int ret;
 
 	/*
 	 * Lock device and try to bind to it. We drop the error
@@ -630,8 +641,17 @@ static int __driver_attach(struct device *dev, void *data)
 	 * is an error.
 	 */
 
-	if (!driver_match_device(drv, dev))
+	ret = driver_match_device(drv, dev);
+	if (!ret)
+		return 0;
+	else if (ret < 0) {
+		if (ret == -EPROBE_DEFER) {
+			dev_dbg(dev, "Device match requests probe deferral\n");
+			driver_deferred_probe_add(dev);
+		} else
+			dev_warn(dev, "Bus failed to match device: %d", ret);
 		return 0;
+	}
 
 	if (dev->parent)	/* Needed for USB */
 		device_lock(dev->parent);
diff --git a/include/linux/device.h b/include/linux/device.h
index 5d7bc6349930..8e7b806f0744 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -70,7 +70,7 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  * @dev_groups:	Default attributes of the devices on the bus.
  * @drv_groups: Default attributes of the device drivers on the bus.
  * @match:	Called, perhaps multiple times, whenever a new device or driver
- *		is added for this bus. It should return a nonzero value if the
+ *		is added for this bus. It should return a positive value if the
  *		given device can be handled by the given driver.
  * @uevent:	Called when a device is added, removed, or a few other things
  *		that generate uevents to add the environment variables.
-- 
2.4.3

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#1229399 — [PATCH v6 15/22] clk: Probe clk providers on demand

When looking up a clock through its OF node, probe it if it hasn't
already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/clk/clk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index b005f666e3a1..8986c9d876a4 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -19,6 +19,7 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/sched.h>
@@ -3005,6 +3006,8 @@ struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
 	if (!clkspec)
 		return ERR_PTR(-EINVAL);
 
+	of_device_probe(clkspec->np);
+
 	/* Check if we have such a provider in our array */
 	mutex_lock(&of_clk_mutex);
 	list_for_each_entry(provider, &of_clk_providers, link) {
-- 
2.4.3

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#1229402 — [PATCH v6 19/22] power-supply: Probe power supplies on demand

When looking up a power supply through its OF node, probe it if it
hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/power/power_supply_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/power/power_supply_core.c b/drivers/power/power_supply_core.c
index 456987c88baa..80bc89f4ae89 100644
--- a/drivers/power/power_supply_core.c
+++ b/drivers/power/power_supply_core.c
@@ -19,6 +19,7 @@
 #include <linux/err.h>
 #include <linux/power_supply.h>
 #include <linux/thermal.h>
+#include <linux/of_device.h>
 #include "power_supply.h"
 
 /* exported for the APM Power driver, APM emulation */
@@ -206,6 +207,8 @@ static int power_supply_find_supply_from_node(struct device_node *supply_node)
 {
 	int error;
 
+	of_device_probe(supply_node);
+
 	/*
 	 * class_for_each_device() either returns its own errors or values
 	 * returned by __power_supply_find_supply_from_node().
-- 
2.4.3

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#1229404 — [PATCH v6 20/22] driver core: Allow deferring probes until late init

Add a field to struct device that instructs the device-driver core to
defer the probe of this device until the late_initcall level.

By letting all built-in drivers to register before starting to probe, we
can avoid any deferred probes by probing dependencies on demand.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>

---

Changes in v4:
- Add Kconfig DELAY_DEVICE_PROBES to allow disabling delayed probing in
  machines with initcalls that depend on devices probing at a given time.

 drivers/base/Kconfig   | 18 ++++++++++++++++++
 drivers/base/dd.c      |  7 +++++++
 include/linux/device.h |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 98504ec99c7d..44b5d33b1f49 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -324,4 +324,22 @@ config CMA_ALIGNMENT
 
 endif
 
+config DELAY_DEVICE_PROBES
+	bool "Allow delaying the probe of some devices"
+	default y
+	help
+	  Devices can be matched to a driver and probed from the moment they
+	  are registered, but early during boot their probes are likely to be
+	  deferred because some dependency isn't available yet because most
+	  drivers haven't been registered yet.
+
+	  Enabling this option allows the device registration code to delay the
+	  probing of a specific device until device_initcall_sync, when all
+	  built-in drivers have been registered already.
+
+	  In some platforms there may be implicit assumptions about when some
+	  devices are probed, so enabling this option could cause problems there.
+
+	  If unsure, say Y here.
+
 endmenu
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 7dc04ee81c8b..269ea76c1a4f 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -417,6 +417,13 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
 	if (!device_is_registered(dev))
 		return -ENODEV;
 
+#if IS_ENABLED(CONFIG_DELAY_DEVICE_PROBES)
+	if (!driver_deferred_probe_enable && dev->probe_late) {
+		driver_deferred_probe_add(dev);
+		return 0;
+	}
+#endif
+
 	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 		 drv->bus->name, __func__, dev_name(dev), drv->name);
 
diff --git a/include/linux/device.h b/include/linux/device.h
index 8e7b806f0744..e64f4c7e243d 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -744,6 +744,7 @@ struct device_dma_parameters {
  *
  * @offline_disabled: If set, the device is permanently online.
  * @offline:	Set after successful invocation of bus type's .offline().
+ * @probe_late:	If set, device will be probed in the late initcall level.
  *
  * At the lowest level, every device in a Linux system is represented by an
  * instance of struct device. The device structure contains the information
@@ -828,6 +829,7 @@ struct device {
 
 	bool			offline_disabled:1;
 	bool			offline:1;
+	bool			probe_late:1;
 };
 
 static inline struct device *kobj_to_dev(struct kobject *kobj)
-- 
2.4.3

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#1229405 — [PATCH v6 16/22] pinctrl: Probe pinctrl devices on demand

When looking up a pin controller through its OF node, probe it if it
hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/pinctrl/devicetree.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index fe04e748dfe4..f5340b8e1dbe 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -18,6 +18,7 @@
 
 #include <linux/device.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
 
@@ -110,6 +111,8 @@ static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
 	struct pinctrl_map *map;
 	unsigned num_maps;
 
+	of_device_probe(np_config);
+
 	/* Find the pin controller containing np_config */
 	np_pctldev = of_node_get(np_config);
 	for (;;) {
-- 
2.4.3

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#1229406 — [PATCH v6 17/22] phy: core: Probe phy providers on demand

When looking up a phy provider through its OF node, probe it if it
hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/phy/phy-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index fc48fac003a6..94e90031d7f3 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -18,6 +18,7 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/phy/phy.h>
 #include <linux/idr.h>
 #include <linux/pm_runtime.h>
@@ -363,6 +364,8 @@ static struct phy *_of_phy_get(struct device_node *np, int index)
 	if (ret)
 		return ERR_PTR(-ENODEV);
 
+	of_device_probe(args.np);
+
 	mutex_lock(&phy_provider_mutex);
 	phy_provider = of_phy_provider_lookup(args.np);
 	if (IS_ERR(phy_provider) || !try_module_get(phy_provider->owner)) {
-- 
2.4.3

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#1229408 — [PATCH v6 21/22] driver core: Start processing deferred probes earlier

Some initcalls in the late level assume that some devices will have
already probed without explicitly checking for that.

After the recent move to defer most device probes when they are
registered, pressure increased in the late initcall level.

By starting the processing of the deferred queue in device_initcall_sync
we increase the chances that the initcalls mentioned before will find
the devices they depend on to have already probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v4:
- Start processing deferred probes in device_initcall_sync

 drivers/base/dd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 269ea76c1a4f..f0ef9233fcd6 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -176,7 +176,7 @@ static void driver_deferred_probe_trigger(void)
  *
  * We don't want to get in the way when the bulk of drivers are getting probed.
  * Instead, this initcall makes sure that deferred probing is delayed until
- * late_initcall time.
+ * device_initcall_sync time.
  */
 static int deferred_probe_initcall(void)
 {
@@ -190,7 +190,7 @@ static int deferred_probe_initcall(void)
 	flush_workqueue(deferred_wq);
 	return 0;
 }
-late_initcall(deferred_probe_initcall);
+device_initcall_sync(deferred_probe_initcall);
 
 static void driver_bound(struct device *dev)
 {
-- 
2.4.3

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#1229411 — [PATCH v6 07/22] regulator: core: Remove regulator_list

As we are already registering a device with regulator_class for each
regulator device, regulator_list is redundant and can be replaced with
calls to class_find_device() and class_for_each_device().

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v6:
- Merge changes to the regulator subsystem's locking so no references
  are leaked between commits.

Changes in v5:
- Use regulator_class' klist of devices instead of regulator_list to
  store and lookup regulator devices.

 drivers/regulator/core.c | 255 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 164 insertions(+), 91 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index e5dbbe2f5212..af045e5a83ef 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -51,7 +51,6 @@
 	pr_debug("%s: " fmt, rdev_get_name(rdev), ##__VA_ARGS__)
 
 static DEFINE_MUTEX(regulator_list_mutex);
-static LIST_HEAD(regulator_list);
 static LIST_HEAD(regulator_map_list);
 static LIST_HEAD(regulator_ena_gpio_list);
 static LIST_HEAD(regulator_supply_alias_list);
@@ -59,6 +58,8 @@ static bool has_full_constraints;
 
 static struct dentry *debugfs_root;
 
+static struct class regulator_class;
+
 /*
  * struct regulator_map
  *
@@ -1325,6 +1326,47 @@ static void regulator_supply_alias(struct device **dev, const char **supply)
 	}
 }
 
+static int of_node_match(struct device *dev, const void *data)
+{
+	return dev->of_node == data;
+}
+
+static struct regulator_dev *of_find_regulator_by_node(struct device_node *np)
+{
+	struct device *dev;
+
+	dev = class_find_device(&regulator_class, NULL, np, of_node_match);
+
+	return dev ? dev_to_rdev(dev) : NULL;
+}
+
+static int regulator_match(struct device *dev, const void *data)
+{
+	struct regulator_dev *r = dev_to_rdev(dev);
+
+	return strcmp(rdev_get_name(r), data) == 0;
+}
+
+static struct regulator_dev *regulator_lookup_by_name(const char *name)
+{
+	struct device *dev;
+
+	dev = class_find_device(&regulator_class, NULL, name, regulator_match);
+
+	return dev ? dev_to_rdev(dev) : NULL;
+}
+
+/**
+ * regulator_dev_lookup - lookup a regulator device.
+ * @dev: device for regulator "consumer".
+ * @supply: Supply name or regulator ID.
+ * @ret: 0 on success, -ENODEV if lookup fails permanently, -EPROBE_DEFER if
+ * lookup could succeed in the future.
+ *
+ * If successful, returns a struct regulator_dev that corresponds to the name
+ * @supply and with the embedded struct device refcount incremented by one,
+ * or NULL on failure. The refcount must be dropped by calling put_device().
+ */
 static struct regulator_dev *regulator_dev_lookup(struct device *dev,
 						  const char *supply,
 						  int *ret)
@@ -1340,10 +1382,9 @@ static struct regulator_dev *regulator_dev_lookup(struct device *dev,
 	if (dev && dev->of_node) {
 		node = of_get_regulator(dev, supply);
 		if (node) {
-			list_for_each_entry(r, &regulator_list, list)
-				if (r->dev.parent &&
-					node == r->dev.of_node)
-					return r;
+			r = of_find_regulator_by_node(node);
+			if (r)
+				return r;
 			*ret = -EPROBE_DEFER;
 			return NULL;
 		} else {
@@ -1361,20 +1402,24 @@ static struct regulator_dev *regulator_dev_lookup(struct device *dev,
 	if (dev)
 		devname = dev_name(dev);
 
-	list_for_each_entry(r, &regulator_list, list)
-		if (strcmp(rdev_get_name(r), supply) == 0)
-			return r;
+	r = regulator_lookup_by_name(supply);
+	if (r)
+		return r;
 
+	mutex_lock(&regulator_list_mutex);
 	list_for_each_entry(map, &regulator_map_list, list) {
 		/* If the mapping has a device set up it must match */
 		if (map->dev_name &&
 		    (!devname || strcmp(map->dev_name, devname)))
 			continue;
 
-		if (strcmp(map->supply, supply) == 0)
+		if (strcmp(map->supply, supply) == 0 &&
+		    get_device(&map->regulator->dev)) {
+			mutex_unlock(&regulator_list_mutex);
 			return map->regulator;
+		}
 	}
-
+	mutex_unlock(&regulator_list_mutex);
 
 	return NULL;
 }
@@ -1405,6 +1450,7 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 
 		if (have_full_constraints()) {
 			r = dummy_regulator_rdev;
+			get_device(&r->dev);
 		} else {
 			dev_err(dev, "Failed to resolve %s-supply for %s\n",
 				rdev->supply_name, rdev->desc->name);
@@ -1414,12 +1460,16 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 
 	/* Recursively resolve the supply of the supply */
 	ret = regulator_resolve_supply(r);
-	if (ret < 0)
+	if (ret < 0) {
+		put_device(&r->dev);
 		return ret;
+	}
 
 	ret = set_supply(rdev, r);
-	if (ret < 0)
+	if (ret < 0) {
+		put_device(&r->dev);
 		return ret;
+	}
 
 	/* Cascade always-on state to supply */
 	if (_regulator_is_enabled(rdev) && rdev->supply) {
@@ -1455,8 +1505,6 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
 	else
 		ret = -EPROBE_DEFER;
 
-	mutex_lock(&regulator_list_mutex);
-
 	rdev = regulator_dev_lookup(dev, id, &ret);
 	if (rdev)
 		goto found;
@@ -1468,7 +1516,7 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
 	 * succeed, so, quit with appropriate error value
 	 */
 	if (ret && ret != -ENODEV)
-		goto out;
+		return regulator;
 
 	if (!devname)
 		devname = "deviceless";
@@ -1482,40 +1530,46 @@ static struct regulator *_regulator_get(struct device *dev, const char *id,
 			devname, id);
 
 		rdev = dummy_regulator_rdev;
+		get_device(&rdev->dev);
 		goto found;
 	/* Don't log an error when called from regulator_get_optional() */
 	} else if (!have_full_constraints() || exclusive) {
 		dev_warn(dev, "dummy supplies not allowed\n");
 	}
 
-	mutex_unlock(&regulator_list_mutex);
 	return regulator;
 
 found:
 	if (rdev->exclusive) {
 		regulator = ERR_PTR(-EPERM);
-		goto out;
+		put_device(&rdev->dev);
+		return regulator;
 	}
 
 	if (exclusive && rdev->open_count) {
 		regulator = ERR_PTR(-EBUSY);
-		goto out;
+		put_device(&rdev->dev);
+		return regulator;
 	}
 
 	ret = regulator_resolve_supply(rdev);
 	if (ret < 0) {
 		regulator = ERR_PTR(ret);
-		goto out;
+		put_device(&rdev->dev);
+		return regulator;
 	}
 
-	if (!try_module_get(rdev->owner))
-		goto out;
+	if (!try_module_get(rdev->owner)) {
+		put_device(&rdev->dev);
+		return regulator;
+	}
 
 	regulator = create_regulator(rdev, dev, id);
 	if (regulator == NULL) {
 		regulator = ERR_PTR(-ENOMEM);
+		put_device(&rdev->dev);
 		module_put(rdev->owner);
-		goto out;
+		return regulator;
 	}
 
 	rdev->open_count++;
@@ -1529,9 +1583,6 @@ found:
 			rdev->use_count = 0;
 	}
 
-out:
-	mutex_unlock(&regulator_list_mutex);
-
 	return regulator;
 }
 
@@ -1629,6 +1680,7 @@ static void _regulator_put(struct regulator *regulator)
 
 	rdev->open_count--;
 	rdev->exclusive = 0;
+	put_device(&rdev->dev);
 	mutex_unlock(&rdev->mutex);
 
 	kfree(regulator->supply_name);
@@ -3806,8 +3858,6 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		}
 	}
 
-	list_add(&rdev->list, &regulator_list);
-
 	rdev_init_debugfs(rdev);
 out:
 	mutex_unlock(&regulator_list_mutex);
@@ -3861,6 +3911,19 @@ void regulator_unregister(struct regulator_dev *rdev)
 }
 EXPORT_SYMBOL_GPL(regulator_unregister);
 
+static int _regulator_suspend_prepare(struct device *dev, void *data)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	const suspend_state_t *state = data;
+	int ret;
+
+	mutex_lock(&rdev->mutex);
+	ret = suspend_prepare(rdev, *state);
+	mutex_unlock(&rdev->mutex);
+
+	return ret;
+}
+
 /**
  * regulator_suspend_prepare - prepare regulators for system wide suspend
  * @state: system suspend state
@@ -3870,30 +3933,45 @@ EXPORT_SYMBOL_GPL(regulator_unregister);
  */
 int regulator_suspend_prepare(suspend_state_t state)
 {
-	struct regulator_dev *rdev;
-	int ret = 0;
-
 	/* ON is handled by regulator active state */
 	if (state == PM_SUSPEND_ON)
 		return -EINVAL;
 
-	mutex_lock(&regulator_list_mutex);
-	list_for_each_entry(rdev, &regulator_list, list) {
+	return class_for_each_device(&regulator_class, NULL, &state,
+				     _regulator_suspend_prepare);
+}
+EXPORT_SYMBOL_GPL(regulator_suspend_prepare);
 
-		mutex_lock(&rdev->mutex);
-		ret = suspend_prepare(rdev, state);
-		mutex_unlock(&rdev->mutex);
+static int _regulator_suspend_finish(struct device *dev, void *data)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	int ret;
 
-		if (ret < 0) {
-			rdev_err(rdev, "failed to prepare\n");
-			goto out;
+	mutex_lock(&rdev->mutex);
+	if (rdev->use_count > 0  || rdev->constraints->always_on) {
+		if (!_regulator_is_enabled(rdev)) {
+			ret = _regulator_do_enable(rdev);
+			if (ret)
+				dev_err(dev,
+					"Failed to resume regulator %d\n",
+					ret);
 		}
+	} else {
+		if (!have_full_constraints())
+			goto unlock;
+		if (!_regulator_is_enabled(rdev))
+			goto unlock;
+
+		ret = _regulator_do_disable(rdev);
+		if (ret)
+			dev_err(dev, "Failed to suspend regulator %d\n", ret);
 	}
-out:
-	mutex_unlock(&regulator_list_mutex);
-	return ret;
+unlock:
+	mutex_unlock(&rdev->mutex);
+
+	/* Keep processing regulators in spite of any errors */
+	return 0;
 }
-EXPORT_SYMBOL_GPL(regulator_suspend_prepare);
 
 /**
  * regulator_suspend_finish - resume regulators from system wide suspend
@@ -3903,33 +3981,8 @@ EXPORT_SYMBOL_GPL(regulator_suspend_prepare);
  */
 int regulator_suspend_finish(void)
 {
-	struct regulator_dev *rdev;
-	int ret = 0, error;
-
-	mutex_lock(&regulator_list_mutex);
-	list_for_each_entry(rdev, &regulator_list, list) {
-		mutex_lock(&rdev->mutex);
-		if (rdev->use_count > 0  || rdev->constraints->always_on) {
-			if (!_regulator_is_enabled(rdev)) {
-				error = _regulator_do_enable(rdev);
-				if (error)
-					ret = error;
-			}
-		} else {
-			if (!have_full_constraints())
-				goto unlock;
-			if (!_regulator_is_enabled(rdev))
-				goto unlock;
-
-			error = _regulator_do_disable(rdev);
-			if (error)
-				ret = error;
-		}
-unlock:
-		mutex_unlock(&rdev->mutex);
-	}
-	mutex_unlock(&regulator_list_mutex);
-	return ret;
+	return class_for_each_device(&regulator_class, NULL, NULL,
+				     _regulator_suspend_finish);
 }
 EXPORT_SYMBOL_GPL(regulator_suspend_finish);
 
@@ -4049,14 +4102,35 @@ static const struct file_operations supply_map_fops = {
 };
 
 #ifdef CONFIG_DEBUG_FS
+struct summary_data {
+	struct seq_file *s;
+	struct regulator_dev *parent;
+	int level;
+};
+
+static void regulator_summary_show_subtree(struct seq_file *s,
+					   struct regulator_dev *rdev,
+					   int level);
+
+static int regulator_summary_show_children(struct device *dev, void *data)
+{
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	struct summary_data *summary_data = data;
+
+	if (rdev->supply && rdev->supply->rdev == summary_data->parent)
+		regulator_summary_show_subtree(summary_data->s, rdev,
+					       summary_data->level + 1);
+
+	return 0;
+}
+
 static void regulator_summary_show_subtree(struct seq_file *s,
 					   struct regulator_dev *rdev,
 					   int level)
 {
-	struct list_head *list = s->private;
-	struct regulator_dev *child;
 	struct regulation_constraints *c;
 	struct regulator *consumer;
+	struct summary_data summary_data;
 
 	if (!rdev)
 		return;
@@ -4106,33 +4180,32 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 		seq_puts(s, "\n");
 	}
 
-	list_for_each_entry(child, list, list) {
-		/* handle only non-root regulators supplied by current rdev */
-		if (!child->supply || child->supply->rdev != rdev)
-			continue;
+	summary_data.s = s;
+	summary_data.level = level;
+	summary_data.parent = rdev;
 
-		regulator_summary_show_subtree(s, child, level + 1);
-	}
+	class_for_each_device(&regulator_class, NULL, &summary_data,
+			      regulator_summary_show_children);
 }
 
-static int regulator_summary_show(struct seq_file *s, void *data)
+static int regulator_summary_show_roots(struct device *dev, void *data)
 {
-	struct list_head *list = s->private;
-	struct regulator_dev *rdev;
-
-	seq_puts(s, " regulator                      use open bypass voltage current     min     max\n");
-	seq_puts(s, "-------------------------------------------------------------------------------\n");
+	struct regulator_dev *rdev = dev_to_rdev(dev);
+	struct seq_file *s = data;
 
-	mutex_lock(&regulator_list_mutex);
+	if (!rdev->supply)
+		regulator_summary_show_subtree(s, rdev, 0);
 
-	list_for_each_entry(rdev, list, list) {
-		if (rdev->supply)
-			continue;
+	return 0;
+}
 
-		regulator_summary_show_subtree(s, rdev, 0);
-	}
+static int regulator_summary_show(struct seq_file *s, void *data)
+{
+	seq_puts(s, " regulator                      use open bypass voltage current     min     max\n");
+	seq_puts(s, "-------------------------------------------------------------------------------\n");
 
-	mutex_unlock(&regulator_list_mutex);
+	class_for_each_device(&regulator_class, NULL, s,
+			      regulator_summary_show_roots);
 
 	return 0;
 }
@@ -4166,7 +4239,7 @@ static int __init regulator_init(void)
 			    &supply_map_fops);
 
 	debugfs_create_file("regulator_summary", 0444, debugfs_root,
-			    &regulator_list, &regulator_summary_fops);
+			    NULL, &regulator_summary_fops);
 
 	regulator_dummy_init();
 
-- 
2.4.3

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#1229691 — Re: [PATCH v6 07/22] regulator: core: Remove regulator_list

[Multipart message — attachments visible in raw view] — view raw

On Mon, Sep 21, 2015 at 04:02:47PM +0200, Tomeu Vizoso wrote:
> As we are already registering a device with regulator_class for each
> regulator device, regulator_list is redundant and can be replaced with
> calls to class_find_device() and class_for_each_device().

I've done an initial review of this and will push it to git so it can go
into the various test systems.  It's on a branch by itself so if there's
issues it's easy to back out, either from testing or from review from me
or others.  If we get to the point of merging the whole series then I'll
tag the code for cross merging.

Thanks a lot for working on this, this is something I'd started looking
at myself and it's a lot easier to just review code from someone else!

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#1229944 — Re: [PATCH v6 07/22] regulator: core: Remove regulator_list

On 21 September 2015 at 21:38, Mark Brown <broonie@kernel.org> wrote:
> On Mon, Sep 21, 2015 at 04:02:47PM +0200, Tomeu Vizoso wrote:
>> As we are already registering a device with regulator_class for each
>> regulator device, regulator_list is redundant and can be replaced with
>> calls to class_find_device() and class_for_each_device().
>
> I've done an initial review of this and will push it to git so it can go
> into the various test systems.  It's on a branch by itself so if there's
> issues it's easy to back out, either from testing or from review from me
> or others.  If we get to the point of merging the whole series then I'll
> tag the code for cross merging.
>
> Thanks a lot for working on this, this is something I'd started looking
> at myself and it's a lot easier to just review code from someone else!

Thanks for your patience, will keep an eye on possible regressions.

Regards,

Tomeu
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#1229412 — [PATCH v6 02/22] ARM: amba: Move reading of periphid to amba_match()

Reading the periphid when the Primecell device is registered means that
the apb pclk must be available by then or the device won't be registered
at all.

By reading the periphid in amba_match() we can return -EPROBE_DEFER if
the apb pclk isn't there yet and the device will be retried later.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v6:
- Drop bus_type.pre_probe and read the periphid in match() instead as
  suggested by Alan Stern.

Changes in v4:
- Added bus.pre_probe callback so the probes of Primecell devices can be
  deferred if their device IDs cannot be yet read because of the clock
  driver not having probed when they are registered. Maybe this goes
  overboard and the matching information should be in the DT if there is
  one.

 drivers/amba/bus.c | 88 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 46 insertions(+), 42 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index f0099360039e..72ebf9b1c715 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -24,6 +24,8 @@
 
 #define to_amba_driver(d)	container_of(d, struct amba_driver, drv)
 
+static int read_periphid(struct amba_device *d, unsigned int *periphid);
+
 static const struct amba_id *
 amba_lookup(const struct amba_id *table, struct amba_device *dev)
 {
@@ -43,11 +45,22 @@ static int amba_match(struct device *dev, struct device_driver *drv)
 {
 	struct amba_device *pcdev = to_amba_device(dev);
 	struct amba_driver *pcdrv = to_amba_driver(drv);
+	int ret;
 
 	/* When driver_override is set, only bind to the matching driver */
 	if (pcdev->driver_override)
 		return !strcmp(pcdev->driver_override, drv->name);
 
+	if (!pcdev->periphid) {
+		ret = read_periphid(pcdev, &pcdev->periphid);
+		if (ret) {
+			if (ret != -EPROBE_DEFER)
+				dev_err(dev, "Failed to read periphid: %d",
+					ret);
+			return ret;
+		}
+	}
+
 	return amba_lookup(pcdrv->id_table, pcdev) != NULL;
 }
 
@@ -336,44 +349,22 @@ static void amba_device_release(struct device *dev)
 	kfree(d);
 }
 
-/**
- *	amba_device_add - add a previously allocated AMBA device structure
- *	@dev: AMBA device allocated by amba_device_alloc
- *	@parent: resource parent for this devices resources
- *
- *	Claim the resource, and read the device cell ID if not already
- *	initialized.  Register the AMBA device with the Linux device
- *	manager.
- */
-int amba_device_add(struct amba_device *dev, struct resource *parent)
+static int read_periphid(struct amba_device *d, unsigned int *periphid)
 {
 	u32 size;
 	void __iomem *tmp;
-	int i, ret;
-
-	WARN_ON(dev->irq[0] == (unsigned int)-1);
-	WARN_ON(dev->irq[1] == (unsigned int)-1);
-
-	ret = request_resource(parent, &dev->res);
-	if (ret)
-		goto err_out;
-
-	/* Hard-coded primecell ID instead of plug-n-play */
-	if (dev->periphid != 0)
-		goto skip_probe;
+	int i, ret = 0;
 
 	/*
 	 * Dynamically calculate the size of the resource
 	 * and use this for iomap
 	 */
-	size = resource_size(&dev->res);
-	tmp = ioremap(dev->res.start, size);
-	if (!tmp) {
-		ret = -ENOMEM;
-		goto err_release;
-	}
+	size = resource_size(&d->res);
+	tmp = ioremap(d->res.start, size);
+	if (!tmp)
+		return -ENOMEM;
 
-	ret = amba_get_enable_pclk(dev);
+	ret = amba_get_enable_pclk(d);
 	if (ret == 0) {
 		u32 pid, cid;
 
@@ -388,37 +379,50 @@ int amba_device_add(struct amba_device *dev, struct resource *parent)
 			cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
 				(i * 8);
 
-		amba_put_disable_pclk(dev);
+		amba_put_disable_pclk(d);
 
 		if (cid == AMBA_CID || cid == CORESIGHT_CID)
-			dev->periphid = pid;
+			*periphid = pid;
 
-		if (!dev->periphid)
+		if (!*periphid)
 			ret = -ENODEV;
 	}
 
 	iounmap(tmp);
 
+	return ret;
+}
+
+/**
+ *	amba_device_add - add a previously allocated AMBA device structure
+ *	@dev: AMBA device allocated by amba_device_alloc
+ *	@parent: resource parent for this devices resources
+ *
+ *	Claim the resource, and register the AMBA device with the Linux device
+ *	manager.
+ */
+int amba_device_add(struct amba_device *dev, struct resource *parent)
+{
+	int ret;
+
+	WARN_ON(dev->irq[0] == (unsigned int)-1);
+	WARN_ON(dev->irq[1] == (unsigned int)-1);
+
+	ret = request_resource(parent, &dev->res);
 	if (ret)
-		goto err_release;
+		return ret;
 
- skip_probe:
 	ret = device_add(&dev->dev);
 	if (ret)
-		goto err_release;
+		return ret;
 
 	if (dev->irq[0])
 		ret = device_create_file(&dev->dev, &dev_attr_irq0);
 	if (ret == 0 && dev->irq[1])
 		ret = device_create_file(&dev->dev, &dev_attr_irq1);
-	if (ret == 0)
-		return ret;
-
-	device_unregister(&dev->dev);
+	if (ret)
+		device_unregister(&dev->dev);
 
- err_release:
-	release_resource(&dev->res);
- err_out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(amba_device_add);
-- 
2.4.3

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#1229413 — [PATCH v6 04/22] of: add function to allow probing a device from a OF node

Walks the OF tree up and finds the closest ancestor that has a struct
device associated with it, probing it if isn't bound to a driver yet.

The above should ensure that the dependency represented by the passed OF
node is available, because probing a device should cause its descendants
to be probed as well (when they get registered).

Subsystems can use this when looking up resources for drivers, to reduce
the chances of deferred probes because of the probing order of devices.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---

Changes in v5:
- Move the assignment to device_node->device for AMBA devices to another
  commit.
- Hold a reference to the struct device while it's in use in
  of_device_probe().

Changes in v4:
- Rename of_platform_probe to of_device_probe
- Use device_node.device instead of device_node.platform_dev

Changes in v3:
- Set and use device_node.platform_dev instead of reversing the logic to
  find the platform device that encloses a device node.
- Drop the fwnode API to probe firmware nodes and add OF-only API for
  now. I think this same scheme could be used for machines with ACPI,
  but I haven't been able to find one that had to defer its probes because
  of the device probe order.

 drivers/of/device.c       | 61 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_device.h |  3 +++
 2 files changed, 64 insertions(+)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 8b91ea241b10..836be71fc90e 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -286,3 +286,64 @@ int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
 
 	return 0;
 }
+
+/**
+ * of_device_probe() - Probe device associated with OF node
+ * @np: node to probe
+ *
+ * Probe the device associated with the passed device node.
+ */
+void of_device_probe(struct device_node *np)
+{
+	struct device_node *target;
+	struct device *dev = NULL;
+
+	if (!of_root || !of_node_check_flag(of_root, OF_POPULATED_BUS))
+		return;
+
+	if (!np)
+		return;
+
+	of_node_get(np);
+
+	/* Find the closest ancestor that has a device associated */
+	for (target = np;
+	     !of_node_is_root(target);
+	     target = of_get_next_parent(target))
+		if (get_device(target->device)) {
+			dev = target->device;
+			break;
+		}
+
+	of_node_put(target);
+
+	if (!dev) {
+		pr_warn("Couldn't find a device for node '%s'\n",
+			of_node_full_name(np));
+		return;
+	}
+
+	/*
+	 * Device is bound or is being probed right now. If we have bad luck
+	 * and the dependency isn't ready when it's needed, deferred probe
+	 * will save us.
+	 */
+	if (dev->driver)
+		goto out;
+
+	/*
+	 * Probing a device should cause its descendants to be probed as
+	 * well, which includes the passed device node.
+	 */
+	if (device_attach(dev) != 1)
+		/*
+		 * This cannot be a warning for now because clock nodes have a
+		 * compatible string but the clock framework doesn't follow
+		 * the device/driver model yet.
+		 */
+		dev_dbg(dev, "Probe failed for %s\n", of_node_full_name(np));
+
+out:
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(of_device_probe);
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index cc7dd687a89d..da8d489e73ad 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -40,6 +40,7 @@ extern ssize_t of_device_get_modalias(struct device *dev,
 
 extern void of_device_uevent(struct device *dev, struct kobj_uevent_env *env);
 extern int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env);
+extern void of_device_probe(struct device_node *np);
 
 static inline void of_device_node_put(struct device *dev)
 {
@@ -84,6 +85,8 @@ static inline int of_device_uevent_modalias(struct device *dev,
 	return -ENODEV;
 }
 
+static inline void of_device_probe(struct device_node *np) { }
+
 static inline void of_device_node_put(struct device *dev) { }
 
 static inline const struct of_device_id *__of_match_device(
-- 
2.4.3

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#1229415 — [PATCH v6 05/22] gpio: Probe GPIO drivers on demand

When looking up a gpiochip through its firmware node, probe it if it
hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/gpio/gpiolib-of.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index fa6e3c8823d6..9a439dab7a87 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -19,6 +19,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
@@ -95,6 +96,8 @@ struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 		return ERR_PTR(ret);
 	}
 
+	of_device_probe(gg_data.gpiospec.np);
+
 	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
 
 	of_node_put(gg_data.gpiospec.np);
-- 
2.4.3

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#1229418 — [PATCH v6 11/22] i2c: core: Probe i2c adapters and devices on demand

When looking up an i2c adapter or device through its OF node, probe it
if it hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/i2c/i2c-core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 5f89f1e3c2f2..02da3acbbd35 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1413,6 +1413,8 @@ struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
 	struct device *dev;
 	struct i2c_client *client;
 
+	of_device_probe(node);
+
 	dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
 	if (!dev)
 		return NULL;
@@ -1431,6 +1433,8 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 	struct device *dev;
 	struct i2c_adapter *adapter;
 
+	of_device_probe(node);
+
 	dev = bus_find_device(&i2c_bus_type, NULL, node, of_dev_node_match);
 	if (!dev)
 		return NULL;
-- 
2.4.3

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#1229419 — [PATCH v6 06/22] gpio: Probe pinctrl devices on demand

When looking up a pin controller through its OF node, probe it if it
hasn't already.

The goal is to reduce deferred probes to a minimum, as it makes it very
cumbersome to find out why a device failed to probe, and can introduce
very big delays in when a critical device is probed.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
---


 drivers/gpio/gpiolib-of.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 9a439dab7a87..05da9a56608d 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -359,6 +359,8 @@ static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 		if (ret)
 			break;
 
+		of_device_probe(pinspec.np);
+
 		pctldev = of_pinctrl_get(pinspec.np);
 		if (!pctldev)
 			return -EPROBE_DEFER;
-- 
2.4.3

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