Re: [PATCH] drm: rcar-du: Make sure DRM planes are created by VSP1

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

Thank you for the patch.

On Friday 03 Mar 2017 09:09:38 Jacopo Mondi wrote:
> On Gen3 platforms compositing planes are allocated  by VSP on behalf of
> DRM/KMS.
> If VSP support is not compiled in, vsp1 initialization stub routine is
> called, leading to invalid memory accesses later on when un-initialized
> planes are accessed.
> 
> Fail explicitly earlier if planes are not properly created.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> b/drivers/gpu/drm/rcar-du/rcar_du_kms.c index b5d3f16..7f56c09 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -616,6 +616,9 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  			ret = rcar_du_vsp_init(vsp);
>  			if (ret < 0)
>  				return ret;
> +
> +			if (!vsp->planes)
> +				return -EINVAL;

Given that this code is only called when the DU hardware requires the VSP to 
operate, how about modifying the rcar_du_vsp_init() stub function to return -
ENXIO instead of 0 ? That way you won't need to add an additional check here.

Ideally we should require VSP through Kconfig as well. If you feel like 
submitting a patch (and testing it with various combinations of module and 
built-in) it would be appreciated.

>  		}
>  	}

-- 
Regards,

Laurent Pinchart