linux-kernel - [PATCH v2 1/2] drm: Improve drm_of_component_probe() to correctly handle ports and remote ports.

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Date:	Fri, 20 Nov 2015 14:22:04 +0000
From:	Liviu Dudau <Liviu.Dudau@....com>
To:	Russell King <rmk+kernel@....linux.org.uk>,
	Mark Yao <mark.yao@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	David Airlie <airlied@...ux.ie>, Eric Anholt <eric@...olt.net>
Cc:	linux-rockchip <linux-rockchip@...ts.infradead.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 1/2] drm: Improve drm_of_component_probe() to correctly handle ports and remote ports.

Rockchip DRM driver cannot use the same compare_of() function to
match ports and remote ports (aka encoders) as their OF sub-trees
look different. Add a second compare function to be used when encoders
are added to the component framework and patch the existing users of
the function accordingly.

Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
---
 drivers/gpu/drm/armada/armada_drv.c |  3 ++-
 drivers/gpu/drm/drm_of.c            | 19 ++++++++++++++-----
 drivers/gpu/drm/imx/imx-drm-core.c  |  3 ++-
 include/drm/drm_of.h                |  6 ++++--
 4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/armada/armada_drv.c b/drivers/gpu/drm/armada/armada_drv.c
index 77ab93d..3a2a929 100644
--- a/drivers/gpu/drm/armada/armada_drv.c
+++ b/drivers/gpu/drm/armada/armada_drv.c
@@ -274,7 +274,8 @@ static int armada_drm_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	int ret;
 
-	ret = drm_of_component_probe(dev, compare_dev_name, &armada_master_ops);
+	ret = drm_of_component_probe(dev, compare_dev_name, compare_dev_name,
+				     &armada_master_ops);
 	if (ret != -EINVAL)
 		return ret;
 
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 493c05c..34589d3 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -77,7 +77,8 @@ EXPORT_SYMBOL(drm_of_find_possible_crtcs);
  * 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 *),
+			   int (*compare_port)(struct device *, void *),
+			   int (*compare_encoder)(struct device *, void *),
 			   const struct component_master_ops *m_ops)
 {
 	struct device_node *ep, *port, *remote;
@@ -101,8 +102,12 @@ int drm_of_component_probe(struct device *dev,
 			continue;
 		}
 
-		component_match_add(dev, &match, compare_of, port);
-		of_node_put(port);
+		component_match_add(dev, &match, compare_port, port);
+		/*
+		 * component_match_add keeps a reference to the port
+		 * variable, so we need to keep the reference count
+		 * increment from of_parse_phandle()
+		 */
 	}
 
 	if (i == 0) {
@@ -140,8 +145,12 @@ int drm_of_component_probe(struct device *dev,
 				continue;
 			}
 
-			component_match_add(dev, &match, compare_of, remote);
-			of_node_put(remote);
+			component_match_add(dev, &match, compare_encoder, remote);
+			/*
+			 * component_match_add keeps a reference to the port
+			 * variable, so we need to keep the reference count
+			 * increment from of_graph_get_remote_port_parent()
+			 */
 		}
 		of_node_put(port);
 	}
diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
index 64f16ea..0d36410 100644
--- a/drivers/gpu/drm/imx/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/imx-drm-core.c
@@ -531,7 +531,8 @@ static const struct component_master_ops imx_drm_ops = {
 
 static int imx_drm_platform_probe(struct platform_device *pdev)
 {
-	int ret = drm_of_component_probe(&pdev->dev, compare_of, &imx_drm_ops);
+	int ret = drm_of_component_probe(&pdev->dev, compare_of, compare_of,
+					 &imx_drm_ops);
 
 	if (!ret)
 		ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index 8544665..1c29e42 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -10,7 +10,8 @@ struct device_node;
 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 *),
+				  int (*compare_port)(struct device *, void *),
+				  int (*compare_encoder)(struct device *, void *),
 				  const struct component_master_ops *m_ops);
 #else
 static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
@@ -21,7 +22,8 @@ static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 
 static inline int
 drm_of_component_probe(struct device *dev,
-		       int (*compare_of)(struct device *, void *),
+		       int (*compare_port)(struct device *, void *),
+		       int (*compare_encoder)(struct device *, void *),
 		       const struct component_master_ops *m_ops)
 {
 	return -EINVAL;
-- 
2.6.2

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