linux-kernel - Re: [PATCH 05/10] drm/sun4i: Explicitly list and check formats supported by the frontend

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Date:   Fri, 23 Mar 2018 11:06:59 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Sean Paul <seanpaul@...omium.org>
Subject: Re: [PATCH 05/10] drm/sun4i: Explicitly list and check formats
 supported by the frontend

On Wed, Mar 21, 2018 at 04:28:59PM +0100, Paul Kocialkowski wrote:
> In order to check whether the frontend supports a specific format, an
> explicit list and a related helper are introduced.
> 
> They are then used to determine whether the frontend can actually support
> the requested format when it was selected to be used.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_backend.c  |  5 ++++
>  drivers/gpu/drm/sun4i/sun4i_frontend.c | 44 ++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/sun4i/sun4i_frontend.h |  1 +
>  3 files changed, 50 insertions(+)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
> index 7703ba989743..1fad0714c70e 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> @@ -532,6 +532,11 @@ static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
>  		struct drm_format_name_buf format_name;
>  
>  		if (sun4i_backend_plane_uses_frontend(plane_state)) {
> +			if (!sun4i_frontend_format_is_supported(fb->format->format)) {
> +				DRM_DEBUG_DRIVER("Frontend plane check failed\n");
> +				return -EINVAL;
> +			}
> +

So you're checking if the frontend doesn't support it and if the
backend doesn't support it. Who supports it then? :)

Like I was saying, this should be moved to the previous patch, within
sun4i_backend_plane_uses_frontend.

> +static const uint32_t sun4i_frontend_formats[] = {
> +	/* RGB */
> +	DRM_FORMAT_XRGB8888,
> +	DRM_FORMAT_BGRX8888,
> +	/* YUV444 */
> +	DRM_FORMAT_YUV444,
> +	DRM_FORMAT_YVU444,
> +	/* YUV422 */
> +	DRM_FORMAT_YUYV,
> +	DRM_FORMAT_YVYU,
> +	DRM_FORMAT_UYVY,
> +	DRM_FORMAT_VYUY,
> +	DRM_FORMAT_NV16,
> +	DRM_FORMAT_NV61,
> +	DRM_FORMAT_YUV422,
> +	DRM_FORMAT_YVU422,
> +	/* YUV420 */
> +	DRM_FORMAT_NV12,
> +	DRM_FORMAT_NV21,
> +	DRM_FORMAT_YUV420,
> +	DRM_FORMAT_YVU420,
> +	/* YUV411 */
> +	DRM_FORMAT_YUV411,
> +	DRM_FORMAT_YVU411,
> +};

I think this list should reflect what the driver currently supports,
not what the hardware supports.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com