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

[Laurent Pinchart]

Hi Biju,

On Fri, Jun 02, 2023 at 07:29:45PM +0000, Biju Das wrote:
> > Subject: [PATCH v2] drm: rcar-du: Use dev_err_probe() to record cause of
> > KMS init errors
> > 
> > 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+renesas at 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);
> 		
> 	dev_err_probe(rcdu->dev, ret, "failed to initialize CMM\n");
> 
> 	similarly for below one.

Oops. I wonder how I missed that, is it fails to even compile. Sorry :-(
I'll post a v2.

> >  		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