Re: [Intel-gfx] [PATCH v2 18/20] drm/edid: detect color formats and CTA revision in all CTA extensions

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

On Tue, May 03, 2022 at 12:24:03PM +0300, Jani Nikula wrote:
> Convert drm_find_cea_extension() to EDID block iterator in color format
> and CTA revision detection. Detect them in all CTA extensions.
> 
> Also parse CTA Data Blocks in DisplayID even if there's no CTA EDID
> extension.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 3b18a6e501df..41f24f4c2d23 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -5447,32 +5447,40 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>  			      const struct edid *edid)
>  {
>  	struct drm_display_info *info = &connector->display_info;
> +	struct drm_edid_iter edid_iter;
>  	const struct cea_db *db;
>  	struct cea_db_iter iter;
>  	const u8 *edid_ext;
>  
> -	edid_ext = drm_find_cea_extension(edid);
> -	if (!edid_ext)
> -		return;
> +	drm_edid_iter_begin(edid, &edid_iter);
> +	drm_edid_iter_for_each(edid_ext, &edid_iter) {
> +		if (edid_ext[0] != CEA_EXT)
> +			continue;
>  
> -	info->cea_rev = edid_ext[1];
> +		if (!info->cea_rev)
> +			info->cea_rev = edid_ext[1];
>  
> -	/* The existence of a CEA block should imply RGB support */
> -	info->color_formats = DRM_COLOR_FORMAT_RGB444;
> +		if (info->cea_rev != edid_ext[1])
> +			DRM_DEBUG_KMS("CEA extension version mismatch %u != %u\n",
> +				      info->cea_rev, edid_ext[1]);
>  
> -	/* CTA DisplayID Data Block does not have byte #3 */
> -	if (edid_ext[0] == CEA_EXT) {
> +		/* The existence of a CTA extension should imply RGB support */
> +		info->color_formats = DRM_COLOR_FORMAT_RGB444;
>  		if (edid_ext[3] & EDID_CEA_YCRCB444)
>  			info->color_formats |= DRM_COLOR_FORMAT_YCBCR444;
>  		if (edid_ext[3] & EDID_CEA_YCRCB422)
>  			info->color_formats |= DRM_COLOR_FORMAT_YCBCR422;
>  	}
> +	drm_edid_iter_end(&edid_iter);
>  
>  	cea_db_iter_edid_begin(edid, &iter);
>  	cea_db_iter_for_each(db, &iter) {
>  		/* FIXME: convert parsers to use struct cea_db */
>  		const u8 *data = (const u8 *)db;
>  
> +		/* The existence of a CTA block should imply RGB support */
> +		info->color_formats = DRM_COLOR_FORMAT_RGB444;

This part seems a bit iffy. DisplayID has its own way to specify the
supported color depths/encodings. So I think eventually we'll just
want to split this into three logical parts: parse CTA ext block,
parse DispID color stuff, parse CTA data blocks.

> +
>  		if (cea_db_is_hdmi_vsdb(db))
>  			drm_parse_hdmi_vsdb_video(connector, data);
>  		if (cea_db_is_hdmi_forum_vsdb(db) ||
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel