Re: [Intel-gfx] [PATCH v7 01/22] drm/edid: fix AVI infoframe aspect ratio handling

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jan 04, 2023 at 12:05:16PM +0200, Jani Nikula wrote:
> We try to avoid sending VICs defined in the later specs in AVI
> infoframes to sinks that conform to the earlier specs, to not upset
> them, and use 0 for the VIC instead. However, we do this detection and
> conversion to 0 too early, as we'll need the actual VIC to figure out
> the aspect ratio.
> 
> In particular, for a mode with 64:27 aspect ratio, 0 for VIC fails the
> AVI infoframe generation altogether with -EINVAL.
> 
> Separate the VIC lookup from the "filtering", and postpone the
> filtering, to use the proper VIC for aspect ratio handling, and the 0
> VIC for the infoframe video code as needed.
> 
> Reported-by: William Tseng <william.tseng@intel.com>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6153
> References: https://lore.kernel.org/r/20220920062316.43162-1-william.tseng@intel.com
> Cc: <stable@vger.kernel.org>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

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

> ---
>  drivers/gpu/drm/drm_edid.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 3841aba17abd..23f7146e6a9b 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -6885,8 +6885,6 @@ static u8 drm_mode_hdmi_vic(const struct drm_connector *connector,
>  static u8 drm_mode_cea_vic(const struct drm_connector *connector,
>  			   const struct drm_display_mode *mode)
>  {
> -	u8 vic;
> -
>  	/*
>  	 * HDMI spec says if a mode is found in HDMI 1.4b 4K modes
>  	 * we should send its VIC in vendor infoframes, else send the
> @@ -6896,13 +6894,18 @@ static u8 drm_mode_cea_vic(const struct drm_connector *connector,
>  	if (drm_mode_hdmi_vic(connector, mode))
>  		return 0;
>  
> -	vic = drm_match_cea_mode(mode);
> +	return drm_match_cea_mode(mode);
> +}
>  
> -	/*
> -	 * HDMI 1.4 VIC range: 1 <= VIC <= 64 (CEA-861-D) but
> -	 * HDMI 2.0 VIC range: 1 <= VIC <= 107 (CEA-861-F). So we
> -	 * have to make sure we dont break HDMI 1.4 sinks.
> -	 */
> +/*
> + * Avoid sending VICs defined in HDMI 2.0 in AVI infoframes to sinks that
> + * conform to HDMI 1.4.
> + *
> + * HDMI 1.4 (CTA-861-D) VIC range: [1..64]
> + * HDMI 2.0 (CTA-861-F) VIC range: [1..107]
> + */
> +static u8 vic_for_avi_infoframe(const struct drm_connector *connector, u8 vic)
> +{
>  	if (!is_hdmi2_sink(connector) && vic > 64)
>  		return 0;
>  
> @@ -6978,7 +6981,7 @@ drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
>  		picture_aspect = HDMI_PICTURE_ASPECT_NONE;
>  	}
>  
> -	frame->video_code = vic;
> +	frame->video_code = vic_for_avi_infoframe(connector, vic);
>  	frame->picture_aspect = picture_aspect;
>  	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
>  	frame->scan_mode = HDMI_SCAN_MODE_UNDERSCAN;
> -- 
> 2.34.1

-- 
Ville Syrjälä
Intel