linux-kernel - Re: [PATCH v2 1/4] drm/amd/display: Remove unnecessary SIGNAL_TYPE_HDMI_TYPE

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Date: Wed, 17 Apr 2024 15:57:28 -0400
From: Harry Wentland <harry.wentland@....com>
To: Andri Yngvason <andri@...vason.is>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 "Pan, Xinhui" <Xinhui.Pan@....com>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Jani Nikula <jani.nikula@...ux.intel.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
 Simon Ser <contact@...rsion.fr>, Werner Sembach <wse@...edocomputers.com>
Subject: Re: [PATCH v2 1/4] drm/amd/display: Remove unnecessary
 SIGNAL_TYPE_HDMI_TYPE_A check



On 2024-01-15 11:05, Andri Yngvason wrote:
> From: Werner Sembach <wse@...edocomputers.com>
> 
> Remove unnecessary SIGNAL_TYPE_HDMI_TYPE_A check that was performed in the
> drm_mode_is_420_only() case, but not in the drm_mode_is_420_also() &&
> force_yuv420_output case.
> 
> Without further knowledge if YCbCr 4:2:0 is supported outside of HDMI,
> there is no reason to use RGB when the display
> reports drm_mode_is_420_only() even on a non HDMI connection.
> 
> This patch also moves both checks in the same if-case. This  eliminates an
> extra else-if-case.
> 
> Signed-off-by: Werner Sembach <wse@...edocomputers.com>
> Signed-off-by: Andri Yngvason <andri@...vason.is>
> Tested-by: Andri Yngvason <andri@...vason.is>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index f6575d7dee971..cc4d1f7f97b98 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -5575,11 +5575,7 @@ static void fill_stream_properties_from_drm_display_mode(
>  	timing_out->v_border_bottom = 0;
>  	/* TODO: un-hardcode */
>  	if (drm_mode_is_420_only(info, mode_in)
> -			&& stream->signal == SIGNAL_TYPE_HDMI_TYPE_A)
> -		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;
> -	else if (drm_mode_is_420_also(info, mode_in)
> -			&& aconnector
> -			&& aconnector->force_yuv420_output)
> +			|| (drm_mode_is_420_also(info, mode_in) && aconnector->force_yuv420_output))

We need to keep the && aconnector NULL check here, otherwise
writeback connectors will blow up.

Harry

>  		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;
>  	else if ((connector->display_info.color_formats & DRM_COLOR_FORMAT_YCBCR444)
>  			&& stream->signal == SIGNAL_TYPE_HDMI_TYPE_A)