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

[Biju Das <biju.das.jz@xxxxxxxxxxxxxx>]

Hi Laurent,

Thanks for the patch.

> 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@xxxxxxxxxxxxxxxx>
> ---
>  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.
Cheers,
Biju

>  		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