[PATCH v2] drm: rcar-du: Use dev_err_probe() to record cause of KMS init errors

[Laurent Pinchart]

The (large) rcar_du_modeset_init() function can fail for many reasons,
two of two involving probe deferral. Use dev_err_probe() in those code
paths to record the cause of the probe deferral, in order to help
debugging probe issues.

Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
---
 drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.c | 4 ++++
 drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c | 8 ++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.c 
b/drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.c
index 12a8839fe3be..5b752adb1b02 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.c
@@ -701,6 +701,10 @@ static int rcar_du_probe(struct platform_device *pdev)
        /* DRM/KMS objects */
        ret = rcar_du_modeset_init(rcdu);
        if (ret < 0) {
+               /*
+                * Don't use dev_err_probe(), as it would overwrite the probe
+                * deferral reason recorded in rcar_du_modeset_init().
+                */
                if (ret != -EPROBE_DEFER)
                        dev_err(&pdev->dev,
                                "failed to initialize DRM/KMS (%d)\n", ret);
diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c 
b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
index adfb36b0e815..a9b01027bf03 100644
--- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c
@@ -932,8 +932,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 
        /* Initialize the Color Management Modules. */
        ret = rcar_du_cmm_init(rcdu);
-       if (ret)
+       if (ret) {
+               dev_err_probe(rcdu->dev, "failed to initialize CMM\n", ret);
                return ret;
+       }
 
        /* Create the CRTCs. */
        for (swindex = 0, hwindex = 0; swindex < rcdu->num_crtcs; ++hwindex) {
@@ -952,8 +954,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 
        /* Initialize the encoders. */
        ret = rcar_du_encoders_init(rcdu);
-       if (ret < 0)
+       if (ret < 0) {
+               dev_err_probe(rcdu->dev, "failed to initialize encoders\n", 
ret);
                return ret;
+       }
 
        if (ret == 0) {
                dev_err(rcdu->dev, "error: no encoder could be initialized\n");
-- 
Regards,

Laurent Pinchart