[PATCH] drm/imx: Match imx-ipuv3-crtc components using device node in platform data

[Philipp Zabel]

The component master driver imx-drm-core matches component devices using
their of_node. Since commit 950b410dd1ab ("gpu: ipu-v3: Fix imx-ipuv3-crtc
module autoloading"), the imx-ipuv3-crtc dev->of_node is not set during
probing. Before that, of_node was set and caused an of: modalias to be
used instead of the platform: modalias, which broke module autoloading.

On the other hand, if dev->of_node is not set yet when the imx-ipuv3-crtc
probe function calls component_add, component matching in imx-drm-core
fails. While dev->of_node will be set once the next component tries to
bring up the component master, imx-drm-core component binding will never
succeed if one of the crtc devices is probed last.

This patch adds an of_node pointer to the component platform data and
matches against the pdata->of_node instead of dev->of_node in imx-drm-core
to work around this problem.

Fixes: 950b410dd1ab ("gpu: ipu-v3: Fix imx-ipuv3-crtc module autoloading")
Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
I don't like this workaround on top of a workaround, and I think
commit 950b410dd1ab should eventually be reverted in favor of another
patch that allows the core code to fall back to a platform: modalias
if the pdev->dev.of_node doesn't have a compatible property set.

As an alternative to applying this patch I would see reverting
commit 407c9eba7897 ("drm/imx: Remove of_node assignment from ipuv3-crtc
driver probe") for now, even though I think it is correct.
---
 drivers/gpu/drm/imx/imx-drm-core.c | 8 ++++++++
 drivers/gpu/ipu-v3/ipu-common.c    | 5 +++--
 include/video/imx-ipu-v3.h         | 2 ++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
index e26dcde..05229b9 100644
--- a/drivers/gpu/drm/imx/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/imx-drm-core.c
@@ -25,6 +25,7 @@
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_of.h>
+#include <video/imx-ipu-v3.h>
 
 #include "imx-drm.h"
 
@@ -444,6 +445,13 @@ static int compare_of(struct device *dev, void *data)
 {
 	struct device_node *np = data;
 
+	/* Special case for DI, dev->of_node may not be set yet */
+	if (strcmp(dev->driver->name, "imx-ipuv3-crtc") == 0) {
+		struct ipu_client_platformdata *pdata = dev->platform_data;
+
+		return pdata->of_node == np;
+	}
+
 	/* Special case for LDB, one device for two channels */
 	if (of_node_cmp(np->name, "lvds-channel") == 0) {
 		np = of_get_parent(np);
diff --git a/drivers/gpu/ipu-v3/ipu-common.c b/drivers/gpu/ipu-v3/ipu-common.c
index abb98c7..99dcacf 100644
--- a/drivers/gpu/ipu-v3/ipu-common.c
+++ b/drivers/gpu/ipu-v3/ipu-common.c
@@ -997,7 +997,7 @@ struct ipu_platform_reg {
 };
 
 /* These must be in the order of the corresponding device tree port nodes */
-static const struct ipu_platform_reg client_reg[] = {
+static struct ipu_platform_reg client_reg[] = {
 	{
 		.pdata = {
 			.csi = 0,
@@ -1048,7 +1048,7 @@ static int ipu_add_client_devices(struct ipu_soc *ipu, unsigned long ipu_base)
 	mutex_unlock(&ipu_client_id_mutex);
 
 	for (i = 0; i < ARRAY_SIZE(client_reg); i++) {
-		const struct ipu_platform_reg *reg = &client_reg[i];
+		struct ipu_platform_reg *reg = &client_reg[i];
 		struct platform_device *pdev;
 		struct device_node *of_node;
 
@@ -1070,6 +1070,7 @@ static int ipu_add_client_devices(struct ipu_soc *ipu, unsigned long ipu_base)
 
 		pdev->dev.parent = dev;
 
+		reg->pdata.of_node = of_node;
 		ret = platform_device_add_data(pdev, &reg->pdata,
 					       sizeof(reg->pdata));
 		if (!ret)
diff --git a/include/video/imx-ipu-v3.h b/include/video/imx-ipu-v3.h
index ad66589..3a2a794 100644
--- a/include/video/imx-ipu-v3.h
+++ b/include/video/imx-ipu-v3.h
@@ -16,6 +16,7 @@
 #include <linux/videodev2.h>
 #include <linux/bitmap.h>
 #include <linux/fb.h>
+#include <linux/of.h>
 #include <media/v4l2-mediabus.h>
 #include <video/videomode.h>
 
@@ -345,6 +346,7 @@ struct ipu_client_platformdata {
 	int dc;
 	int dp;
 	int dma[2];
+	struct device_node *of_node;
 };
 
 #endif /* __DRM_IPU_H__ */
-- 
2.8.0.rc3