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[PATCH v5 0/5] drm/dsi: DSI for devices with different control bus

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  [PATCH v5 0/5] drm/dsi: DSI for devices with different control bus Archit Taneja <architt@codeaurora.org> - 2016-02-12 10:20 +0100
    [PATCH v5 4/5] drm/dsi: Add routine to unregister a DSI device Archit Taneja <architt@codeaurora.org> - 2016-02-12 10:20 +0100
    [PATCH v5 5/5] drm/dsi: Get DSI host by DT device node Archit Taneja <architt@codeaurora.org> - 2016-02-12 10:20 +0100
    [PATCH v5 1/5] drm/dsi: check for CONFIG_OF when defining of_mipi_dsi_device_add Archit Taneja <architt@codeaurora.org> - 2016-02-12 10:30 +0100

#1332600 — [PATCH v5 0/5] drm/dsi: DSI for devices with different control bus

We are currently restricted when it comes to supporting DSI on devices
that have a non-DSI control bus. For example, DSI encoder chips are
available in the market that are configured via i2c. Configuring their
registers via DSI bus is either optional or not available at all.

These devices still need to pass DSI parameters (data lanes, mode flags
etc) to the DSI host they are connected to. We don't have a way to do
that at the moment.

After some discussions on the previous RFC[1], we decided to support this
by providing additional API in drm_mipi_dsi.c which lets us create new DSI
devices without the need of them to have a DT node.

[1]: https://lkml.org/lkml/2015/6/30/42

Changes in v5:
- Simplify refactoring as suggested by Thierry.
- Use abbreviations correctly.
- Drop "drm/dsi: Check for used channels"
- Return the correct encoded error code for of_mipi_dsi_device_add
  when CONFIG_OF is disabled.
- Use mipi_dsi_device_unregister to implement mipi_dsi_remove_device_fn()
  too.

Changes in v4:
- Added a new patch that fixes build issues when CONFIG_OF is not set.

Changes in v3:

- Incorporated misc comments by Andrzej. Changed from RFC to a PATCH set.
- Fixed htmldocs warnings.


Archit Taneja (5):
  drm/dsi: check for CONFIG_OF when defining of_mipi_dsi_device_add
  drm/dsi: Use mipi_dsi_device_register_full for DSI device creation
  drm/dsi: Try to match non-DT DSI devices
  drm/dsi: Add routine to unregister a DSI device
  drm/dsi: Get DSI host by DT device node

 drivers/gpu/drm/drm_mipi_dsi.c | 127 +++++++++++++++++++++++++++++++++++++----
 include/drm/drm_mipi_dsi.h     |  26 +++++++++
 2 files changed, 141 insertions(+), 12 deletions(-)

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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#1332603 — [PATCH v5 4/5] drm/dsi: Add routine to unregister a DSI device

A driver calling mipi_dsi_device_register_full might want to unregister
the device once it's done. It might also require it in an error handling
path in case something didn't go right.

Create mipi_dsi_device_unregister for this purpse, use it within
mipi_dsi_remove_device_fn as it does the same thing.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 12 +++++++++++-
 include/drm/drm_mipi_dsi.h     |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 42a7aac..f2f5a6d 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -225,6 +225,16 @@ mipi_dsi_device_register_full(struct mipi_dsi_host *host,
 }
 EXPORT_SYMBOL(mipi_dsi_device_register_full);
 
+/**
+ * mipi_dsi_device_unregister - unregister MIPI DSI device
+ * @dsi: DSI peripheral device
+ */
+void mipi_dsi_device_unregister(struct mipi_dsi_device *dsi)
+{
+	device_unregister(&dsi->dev);
+}
+EXPORT_SYMBOL(mipi_dsi_device_unregister);
+
 int mipi_dsi_host_register(struct mipi_dsi_host *host)
 {
 	struct device_node *node;
@@ -244,7 +254,7 @@ static int mipi_dsi_remove_device_fn(struct device *dev, void *priv)
 {
 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);
 
-	device_unregister(&dsi->dev);
+	mipi_dsi_device_unregister(dsi);
 
 	return 0;
 }
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index a914116..06e0a93 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -210,6 +210,7 @@ static inline int mipi_dsi_pixel_format_to_bpp(enum mipi_dsi_pixel_format fmt)
 struct mipi_dsi_device *
 mipi_dsi_device_register_full(struct mipi_dsi_host *host,
 			      const struct mipi_dsi_device_info *info);
+void mipi_dsi_device_unregister(struct mipi_dsi_device *dsi);
 struct mipi_dsi_device *of_find_mipi_dsi_device_by_node(struct device_node *np);
 int mipi_dsi_attach(struct mipi_dsi_device *dsi);
 int mipi_dsi_detach(struct mipi_dsi_device *dsi);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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#1332604 — [PATCH v5 5/5] drm/dsi: Get DSI host by DT device node

MIPI DSI devices are inherently aware of their host because they share a
parent-child hierarchy in the device tree.

Non-DSI drivers that create DSI device don't have this data. In order to
get this information, they require to a phandle to the DSI host in the
device tree.

Maintain a list of all the hosts DSI that are currently registered. This
list will be used to find the mipi_dsi_host corresponding to the
device_node passed in of_find_mipi_dsi_host_by_node.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 39 +++++++++++++++++++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  3 +++
 2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index f2f5a6d..f5d8083 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -235,6 +235,37 @@ void mipi_dsi_device_unregister(struct mipi_dsi_device *dsi)
 }
 EXPORT_SYMBOL(mipi_dsi_device_unregister);
 
+static DEFINE_MUTEX(host_lock);
+static LIST_HEAD(host_list);
+
+/**
+ * of_find_mipi_dsi_host_by_node() - find the MIPI DSI host matching a
+ *				     device tree node
+ * @node: device tree node
+ *
+ * Returns:
+ * A pointer to the MIPI DSI host corresponding to @node or NULL if no
+ * such device exists (or has not been registered yet).
+ */
+struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node)
+{
+	struct mipi_dsi_host *host;
+
+	mutex_lock(&host_lock);
+
+	list_for_each_entry(host, &host_list, list) {
+		if (host->dev->of_node == node) {
+			mutex_unlock(&host_lock);
+			return host;
+		}
+	}
+
+	mutex_unlock(&host_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_find_mipi_dsi_host_by_node);
+
 int mipi_dsi_host_register(struct mipi_dsi_host *host)
 {
 	struct device_node *node;
@@ -246,6 +277,10 @@ int mipi_dsi_host_register(struct mipi_dsi_host *host)
 		of_mipi_dsi_device_add(host, node);
 	}
 
+	mutex_lock(&host_lock);
+	list_add_tail(&host->list, &host_list);
+	mutex_unlock(&host_lock);
+
 	return 0;
 }
 EXPORT_SYMBOL(mipi_dsi_host_register);
@@ -262,6 +297,10 @@ static int mipi_dsi_remove_device_fn(struct device *dev, void *priv)
 void mipi_dsi_host_unregister(struct mipi_dsi_host *host)
 {
 	device_for_each_child(host->dev, NULL, mipi_dsi_remove_device_fn);
+
+	mutex_lock(&host_lock);
+	list_del_init(&host->list);
+	mutex_unlock(&host_lock);
 }
 EXPORT_SYMBOL(mipi_dsi_host_unregister);
 
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 06e0a93..7a9840f 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -96,14 +96,17 @@ struct mipi_dsi_host_ops {
  * struct mipi_dsi_host - DSI host device
  * @dev: driver model device node for this DSI host
  * @ops: DSI host operations
+ * @list: list management
  */
 struct mipi_dsi_host {
 	struct device *dev;
 	const struct mipi_dsi_host_ops *ops;
+	struct list_head list;
 };
 
 int mipi_dsi_host_register(struct mipi_dsi_host *host);
 void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
+struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
 
 /* DSI mode flags */
 
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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#1332611 — [PATCH v5 1/5] drm/dsi: check for CONFIG_OF when defining of_mipi_dsi_device_add

of_mipi_dsi_device_add is used only when CONFIG_OF is enabled. It
currently works if OF support is disabled, but this will change
when we add more functionality to it.

Define the original func if CONFIG_OF is enabled. Define a dummy func
otherwise.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 6e6a9c5..4f2a704 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -129,6 +129,7 @@ static int mipi_dsi_device_add(struct mipi_dsi_device *dsi)
 	return device_add(&dsi->dev);
 }
 
+#if IS_ENABLED(CONFIG_OF)
 static struct mipi_dsi_device *
 of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
 {
@@ -170,6 +171,13 @@ of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
 
 	return dsi;
 }
+#else
+static struct mipi_dsi_device *
+of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
+{
+	return ERR_PTR(-ENODEV);
+}
+#endif
 
 int mipi_dsi_host_register(struct mipi_dsi_host *host)
 {
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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