linux-kernel - Re: [PATCH 2/8] drm/sun4i: backend: Allow a NULL plane pointer to retrieve the format

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Date:   Wed, 13 Dec 2017 17:03:39 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        thomas@...sch.nl
Subject: Re: [PATCH 2/8] drm/sun4i: backend: Allow a NULL plane pointer to
 retrieve the format

On 13/12/2017 16:33, Maxime Ripard wrote:
> The function converting the DRM format to its equivalent in the backend
> registers was assuming that we were having a plane.
> 
> However, we might want to use that function when setting up a plane using
> the frontend, in which case we will not have a plane associated to the
> backend's layer. Yet, we still need to setup the format to the one output
> by the frontend.
> 
> Test for NULL plane pointers before referencing them, so that we can work
> around it.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_backend.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
> index c99d1a7e815a..f971d3fb5ee4 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> @@ -93,7 +93,7 @@ void sun4i_backend_layer_enable(struct sun4i_backend *backend,
>  static int sun4i_backend_drm_format_to_layer(struct drm_plane *plane,
>  					     u32 format, u32 *mode)
>  {
> -	if ((plane->type == DRM_PLANE_TYPE_PRIMARY) &&
> +	if (plane && (plane->type == DRM_PLANE_TYPE_PRIMARY) &&
>  	    (format == DRM_FORMAT_ARGB8888))
>  		format = DRM_FORMAT_XRGB8888;
>  
> 

Reviewed-by: Neil Armstrong <narmstrong@...libre.com>