linux-kernel - Re: [PATCH 1/3] drm: Trust format_mod_supported() when it OKs a plane modifier.

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Message-ID: <20180522163127.GH23723@intel.com>
Date:   Tue, 22 May 2018 19:31:27 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] drm: Trust format_mod_supported() when it OKs a
 plane modifier.

On Fri, Mar 16, 2018 at 03:04:33PM -0700, Eric Anholt wrote:
> For parameterized modifiers (Broadcom's SAND and UIF), we need to
> allow the parameter fields to be filled in, while exposing only the
> variant of the modifier with the parameter unfilled in the internal
> arrays and the format blob.
> 
> Signed-off-by: Eric Anholt <eric@...olt.net>
> Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>

With https://patchwork.freedesktop.org/series/40207/ this should be
safe for i915, so

Reviewed-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

> ---
>  drivers/gpu/drm/drm_plane.c | 23 ++++++++++++-----------
>  include/drm/drm_plane.h     |  5 ++++-
>  2 files changed, 16 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index 46fbd019a337..5bb501f1aae8 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -561,19 +561,20 @@ int drm_plane_check_pixel_format(struct drm_plane *plane,
>  	if (i == plane->format_count)
>  		return -EINVAL;
>  
> -	if (!plane->modifier_count)
> -		return 0;
> +	if (plane->funcs->format_mod_supported) {
> +		if (!plane->funcs->format_mod_supported(plane, format, modifier))
> +			return -EINVAL;
> +	} else {
> +		if (!plane->modifier_count)
> +			return 0;
>  
> -	for (i = 0; i < plane->modifier_count; i++) {
> -		if (modifier == plane->modifiers[i])
> -			break;
> +		for (i = 0; i < plane->modifier_count; i++) {
> +			if (modifier == plane->modifiers[i])
> +				break;
> +		}
> +		if (i == plane->modifier_count)
> +			return -EINVAL;
>  	}
> -	if (i == plane->modifier_count)
> -		return -EINVAL;
> -
> -	if (plane->funcs->format_mod_supported &&
> -	    !plane->funcs->format_mod_supported(plane, format, modifier))
> -		return -EINVAL;
>  
>  	return 0;
>  }
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index f7bf4a48b1c3..6b1b51645f75 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -420,7 +420,10 @@ struct drm_plane_funcs {
>  	 * This optional hook is used for the DRM to determine if the given
>  	 * format/modifier combination is valid for the plane. This allows the
>  	 * DRM to generate the correct format bitmask (which formats apply to
> -	 * which modifier).
> +	 * which modifier), and to valdiate modifiers at atomic_check time.
> +	 *
> +	 * If not present, then any modifier in the plane's modifier
> +	 * list is allowed with any of the plane's formats.
>  	 *
>  	 * Returns:
>  	 *
> -- 
> 2.16.2

-- 
Ville Syrjälä
Intel