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[RFC PATCH v3 0/4] drm: Cleanup probe function for component based masters.

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  [RFC PATCH v3 0/4] drm: Cleanup probe function for component based masters. Liviu Dudau <Liviu.Dudau@arm.com> - 2015-10-19 17:10 +0200
    [RFC PATCH v3 2/4] drm/imx: Convert the probe function to the generic drm_of_component_probe() Liviu Dudau <Liviu.Dudau@arm.com> - 2015-10-19 17:10 +0200
      Re: [RFC PATCH v3 2/4] drm/imx: Convert the probe function to the  generic drm_of_component_probe() Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 17:20 +0200
    [RFC PATCH v3 1/4] drm: Introduce generic probe function for component based masters. Liviu Dudau <Liviu.Dudau@arm.com> - 2015-10-19 17:10 +0200
      Re: [RFC PATCH v3 1/4] drm: Introduce generic probe function for  component based masters. Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 17:20 +0200
      Re: [RFC PATCH v3 1/4] drm: Introduce generic probe function for component based masters. Eric Anholt <eric@anholt.net> - 2015-10-20 11:50 +0200
    [RFC PATCH v3 3/4] drm/rockchip: Convert the probe function to the generic drm_of_component_probe() Liviu Dudau <Liviu.Dudau@arm.com> - 2015-10-19 17:10 +0200

#1250794 — [RFC PATCH v3 0/4] drm: Cleanup probe function for component based masters.

Changelog:
v3: Removed the call to dma_set_coherent_mask() from the generic
    drm_of_component_probe(). Also changes to shorten lines over 80 chars long.
v2: Rebased the patchset on top of drm-next rather than Linus' latest -rc

A few drivers in drivers/gpu/drm are component-enabled and use quite similar
code sequences to probe for their encoder slaves at the remote end of the ports.
Move the code into a "generic" function and remove it from the drivers.

The end results is that drivers get a reference count fix (imx), more thorough
error checking (imx again) plus a decrease in the overall count of LoC.

I'm looking for comments and testing of the patchset (only compile tested from my
end as I don't have access to all the devices touched by the changes). My main
interest is in finding out if -EINVAL is the correct code to return if
dev->of_node == NULL (handy now, as it is different from the other possible error
codes and used in armada to trigger old platform_data support. Also looking for
thoughts on the correctness of the patch and if it possible to co-opt more drivers
into using the function.

Best regards,
Liviu

Liviu Dudau (4):
  drm: Introduce generic probe function for component based masters.
  drm/imx: Convert the probe function to the generic drm_of_component_probe()
  drm/rockchip: Convert the probe function to the generic drm_of_component_probe()
  drm/armada: Convert the probe function to the generic drm_of_component_probe()

 drivers/gpu/drm/armada/armada_drv.c         | 73 ++++++++----------------
 drivers/gpu/drm/drm_of.c                    | 88 +++++++++++++++++++++++++++++
 drivers/gpu/drm/imx/imx-drm-core.c          | 55 ++----------------
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 81 ++------------------------
 include/drm/drm_of.h                        | 13 +++++
 5 files changed, 133 insertions(+), 177 deletions(-)

-- 
2.6.0

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#1250795 — [RFC PATCH v3 2/4] drm/imx: Convert the probe function to the generic drm_of_component_probe()

The generic function is functionally equivalent to the driver's
imx_drm_platform_probe(). Use the generic function and reduce the
overall code size.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/gpu/drm/imx/imx-drm-core.c | 55 +++-----------------------------------
 1 file changed, 4 insertions(+), 51 deletions(-)

diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
index de00a6c..64f16ea 100644
--- a/drivers/gpu/drm/imx/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/imx-drm-core.c
@@ -531,59 +531,12 @@ static const struct component_master_ops imx_drm_ops = {
 
 static int imx_drm_platform_probe(struct platform_device *pdev)
 {
-	struct device_node *ep, *port, *remote;
-	struct component_match *match = NULL;
-	int ret;
-	int i;
-
-	/*
-	 * Bind the IPU display interface ports first, so that
-	 * imx_drm_encoder_parse_of called from encoder .bind callbacks
-	 * works as expected.
-	 */
-	for (i = 0; ; i++) {
-		port = of_parse_phandle(pdev->dev.of_node, "ports", i);
-		if (!port)
-			break;
-
-		component_match_add(&pdev->dev, &match, compare_of, port);
-	}
+	int ret = drm_of_component_probe(&pdev->dev, compare_of, &imx_drm_ops);
 
-	if (i == 0) {
-		dev_err(&pdev->dev, "missing 'ports' property\n");
-		return -ENODEV;
-	}
+	if (!ret)
+		ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
 
-	/* Then bind all encoders */
-	for (i = 0; ; i++) {
-		port = of_parse_phandle(pdev->dev.of_node, "ports", i);
-		if (!port)
-			break;
-
-		for_each_child_of_node(port, ep) {
-			remote = of_graph_get_remote_port_parent(ep);
-			if (!remote || !of_device_is_available(remote)) {
-				of_node_put(remote);
-				continue;
-			} else if (!of_device_is_available(remote->parent)) {
-				dev_warn(&pdev->dev, "parent device of %s is not available\n",
-					 remote->full_name);
-				of_node_put(remote);
-				continue;
-			}
-
-			component_match_add(&pdev->dev, &match, compare_of,
-					    remote);
-			of_node_put(remote);
-		}
-		of_node_put(port);
-	}
-
-	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
-	if (ret)
-		return ret;
-
-	return component_master_add_with_match(&pdev->dev, &imx_drm_ops, match);
+	return ret;
 }
 
 static int imx_drm_platform_remove(struct platform_device *pdev)
-- 
2.6.0

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#1250806 — Re: [RFC PATCH v3 2/4] drm/imx: Convert the probe function to the generic drm_of_component_probe()

On Mon, Oct 19, 2015 at 04:07:48PM +0100, Liviu Dudau wrote:
> The generic function is functionally equivalent to the driver's
> imx_drm_platform_probe(). Use the generic function and reduce the
> overall code size.

Looks fine, thanks.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

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#1250797 — [RFC PATCH v3 1/4] drm: Introduce generic probe function for component based masters.

A lot of component based DRM drivers use a variant of the same code
as the probe function. They bind the crtc ports in the first iteration
and then scan through the child nodes and bind the encoders attached
to the remote endpoints. Factor the common code into a separate
function called drm_of_component_probe() in order to increase code
reuse.

Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/gpu/drm/drm_of.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_of.h     | 13 +++++++
 2 files changed, 101 insertions(+)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index be38840..493c05c 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -1,3 +1,4 @@
+#include <linux/component.h>
 #include <linux/export.h>
 #include <linux/list.h>
 #include <linux/of_graph.h>
@@ -61,3 +62,90 @@ uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 	return possible_crtcs;
 }
 EXPORT_SYMBOL(drm_of_find_possible_crtcs);
+
+/**
+ * drm_of_component_probe - Generic probe function for a component based master
+ * @dev: master device containing the OF node
+ * @compare_of: compare function used for matching components
+ * @master_ops: component master ops to be used
+ *
+ * Parse the platform device OF node and bind all the components associated
+ * with the master. Interface ports are added before the encoders in order to
+ * satisfy their .bind requirements
+ * See Documentation/devicetree/bindings/graph.txt for the bindings.
+ *
+ * Returns zero if successful, or one of the standard error codes if it fails.
+ */
+int drm_of_component_probe(struct device *dev,
+			   int (*compare_of)(struct device *, void *),
+			   const struct component_master_ops *m_ops)
+{
+	struct device_node *ep, *port, *remote;
+	struct component_match *match = NULL;
+	int i;
+
+	if (!dev->of_node)
+		return -EINVAL;
+
+	/*
+	 * Bind the crtc's ports first, so that drm_of_find_possible_crtcs()
+	 * called from encoder's .bind callbacks works as expected
+	 */
+	for (i = 0; ; i++) {
+		port = of_parse_phandle(dev->of_node, "ports", i);
+		if (!port)
+			break;
+
+		if (!of_device_is_available(port->parent)) {
+			of_node_put(port);
+			continue;
+		}
+
+		component_match_add(dev, &match, compare_of, port);
+		of_node_put(port);
+	}
+
+	if (i == 0) {
+		dev_err(dev, "missing 'ports' property\n");
+		return -ENODEV;
+	}
+
+	if (!match) {
+		dev_err(dev, "no available port\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * For bound crtcs, bind the encoders attached to their remote endpoint
+	 */
+	for (i = 0; ; i++) {
+		port = of_parse_phandle(dev->of_node, "ports", i);
+		if (!port)
+			break;
+
+		if (!of_device_is_available(port->parent)) {
+			of_node_put(port);
+			continue;
+		}
+
+		for_each_child_of_node(port, ep) {
+			remote = of_graph_get_remote_port_parent(ep);
+			if (!remote || !of_device_is_available(remote)) {
+				of_node_put(remote);
+				continue;
+			} else if (!of_device_is_available(remote->parent)) {
+				dev_warn(dev, "parent device of %s is not available\n",
+					 remote->full_name);
+				of_node_put(remote);
+				continue;
+			}
+
+			component_match_add(dev, &match, compare_of, remote);
+			of_node_put(remote);
+		}
+		of_node_put(port);
+	}
+
+	return component_master_add_with_match(dev, m_ops, match);
+}
+EXPORT_SYMBOL(drm_of_component_probe);
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index 2441f71..8544665 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -1,18 +1,31 @@
 #ifndef __DRM_OF_H__
 #define __DRM_OF_H__
 
+struct component_master_ops;
+struct device;
 struct drm_device;
 struct device_node;
 
 #ifdef CONFIG_OF
 extern uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 					   struct device_node *port);
+extern int drm_of_component_probe(struct device *dev,
+				  int (*compare_of)(struct device *, void *),
+				  const struct component_master_ops *m_ops);
 #else
 static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 						  struct device_node *port)
 {
 	return 0;
 }
+
+static inline int
+drm_of_component_probe(struct device *dev,
+		       int (*compare_of)(struct device *, void *),
+		       const struct component_master_ops *m_ops)
+{
+	return -EINVAL;
+}
 #endif
 
 #endif /* __DRM_OF_H__ */
-- 
2.6.0

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#1250814 — Re: [RFC PATCH v3 1/4] drm: Introduce generic probe function for component based masters.

On Mon, Oct 19, 2015 at 04:07:47PM +0100, Liviu Dudau wrote:
> A lot of component based DRM drivers use a variant of the same code
> as the probe function. They bind the crtc ports in the first iteration
> and then scan through the child nodes and bind the encoders attached
> to the remote endpoints. Factor the common code into a separate
> function called drm_of_component_probe() in order to increase code
> reuse.

Thanks, this now looks perfect.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

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#1251540 — Re: [RFC PATCH v3 1/4] drm: Introduce generic probe function for component based masters.

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

Liviu Dudau <Liviu.Dudau@arm.com> writes:

> A lot of component based DRM drivers use a variant of the same code
> as the probe function. They bind the crtc ports in the first iteration
> and then scan through the child nodes and bind the encoders attached
> to the remote endpoints. Factor the common code into a separate
> function called drm_of_component_probe() in order to increase code
> reuse.
>
> Cc: David Airlie <airlied@linux.ie>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

Acked-by: Eric Anholt <eric@anholt.net>

I'm unimpressed with of-graph, but this will really help me in trying it
out for vc4.

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#1250801 — [RFC PATCH v3 3/4] drm/rockchip: Convert the probe function to the generic drm_of_component_probe()

Use the generic drm_of_component_probe() function to probe for components.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 81 +++--------------------------
 1 file changed, 6 insertions(+), 75 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index f22e1e1..d26e0cc 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -19,6 +19,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
+#include <drm/drm_of.h>
 #include <linux/dma-mapping.h>
 #include <linux/pm_runtime.h>
 #include <linux/module.h>
@@ -418,29 +419,6 @@ static int compare_of(struct device *dev, void *data)
 	return dev->of_node == np;
 }
 
-static void rockchip_add_endpoints(struct device *dev,
-				   struct component_match **match,
-				   struct device_node *port)
-{
-	struct device_node *ep, *remote;
-
-	for_each_child_of_node(port, ep) {
-		remote = of_graph_get_remote_port_parent(ep);
-		if (!remote || !of_device_is_available(remote)) {
-			of_node_put(remote);
-			continue;
-		} else if (!of_device_is_available(remote->parent)) {
-			dev_warn(dev, "parent device of %s is not available\n",
-				 remote->full_name);
-			of_node_put(remote);
-			continue;
-		}
-
-		component_match_add(dev, match, compare_of, remote);
-		of_node_put(remote);
-	}
-}
-
 static int rockchip_drm_bind(struct device *dev)
 {
 	struct drm_device *drm;
@@ -483,61 +461,14 @@ static const struct component_master_ops rockchip_drm_ops = {
 
 static int rockchip_drm_platform_probe(struct platform_device *pdev)
 {
-	struct device *dev = &pdev->dev;
-	struct component_match *match = NULL;
-	struct device_node *np = dev->of_node;
-	struct device_node *port;
-	int i;
-
-	if (!np)
-		return -ENODEV;
-	/*
-	 * Bind the crtc ports first, so that
-	 * drm_of_find_possible_crtcs called from encoder .bind callbacks
-	 * works as expected.
-	 */
-	for (i = 0;; i++) {
-		port = of_parse_phandle(np, "ports", i);
-		if (!port)
-			break;
-
-		if (!of_device_is_available(port->parent)) {
-			of_node_put(port);
-			continue;
-		}
-
-		component_match_add(dev, &match, compare_of, port->parent);
-		of_node_put(port);
-	}
+	int ret = drm_of_component_probe(&pdev->dev, compare_of,
+					 &rockchip_drm_ops);
 
-	if (i == 0) {
-		dev_err(dev, "missing 'ports' property\n");
+	/* keep compatibility with old code that was returning -ENODEV */
+	if (ret == -EINVAL)
 		return -ENODEV;
-	}
 
-	if (!match) {
-		dev_err(dev, "No available vop found for display-subsystem.\n");
-		return -ENODEV;
-	}
-	/*
-	 * For each bound crtc, bind the encoders attached to its
-	 * remote endpoint.
-	 */
-	for (i = 0;; i++) {
-		port = of_parse_phandle(np, "ports", i);
-		if (!port)
-			break;
-
-		if (!of_device_is_available(port->parent)) {
-			of_node_put(port);
-			continue;
-		}
-
-		rockchip_add_endpoints(dev, &match, port);
-		of_node_put(port);
-	}
-
-	return component_master_add_with_match(dev, &rockchip_drm_ops, match);
+	return ret;
 }
 
 static int rockchip_drm_platform_remove(struct platform_device *pdev)
-- 
2.6.0

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