Re: [PATCH] drm/edid: Use struct cea_db when parsing HDMI VSDB

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sat, 17 Jan 2026, Joshua Peisach <jpeisach@ubuntu.com> wrote:
> drm_parse_hdmi_vsdb_video is one of the parsers that still do not use the
> cea_db struct, and currently passes a u8 pointer.
>
> Set the correct struct type and update references to the data accordingly.
> This also makes the same change to drm_parse_hdmi_deep_color_info as
> necessary.
>
> Signed-off-by: Joshua Peisach <jpeisach@ubuntu.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 26bb7710a..15bd99e65 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -6290,7 +6290,7 @@ static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
>  }
>  
>  static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
> -					   const u8 *hdmi)
> +					   const struct cea_db *db)
>  {
>  	struct drm_display_info *info = &connector->display_info;
>  	unsigned int dc_bpc = 0;
> @@ -6298,24 +6298,24 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>  	/* HDMI supports at least 8 bpc */
>  	info->bpc = 8;
>  
> -	if (cea_db_payload_len(hdmi) < 6)
> +	if (cea_db_payload_len(db) < 6)
>  		return;
>  
> -	if (hdmi[6] & DRM_EDID_HDMI_DC_30) {
> +	if (db->data[6] & DRM_EDID_HDMI_DC_30) {

That's not the same thing, but off-by-one now. Ditto everywhere that
changes from u8* to db->data[].

The main problem with the change (even with fixed offsets) is that the
*specs* typically use indexing from the beginning of the data block, not
from the beginning of payload data.

We've discussed this before with Ville (Cc'd) but I'm not sure if we
reached a conclusion.

BR,
Jani.


>  		dc_bpc = 10;
>  		info->edid_hdmi_rgb444_dc_modes |= DRM_EDID_HDMI_DC_30;
>  		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI sink does deep color 30.\n",
>  			    connector->base.id, connector->name);
>  	}
>  
> -	if (hdmi[6] & DRM_EDID_HDMI_DC_36) {
> +	if (db->data[6] & DRM_EDID_HDMI_DC_36) {
>  		dc_bpc = 12;
>  		info->edid_hdmi_rgb444_dc_modes |= DRM_EDID_HDMI_DC_36;
>  		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI sink does deep color 36.\n",
>  			    connector->base.id, connector->name);
>  	}
>  
> -	if (hdmi[6] & DRM_EDID_HDMI_DC_48) {
> +	if (db->data[6] & DRM_EDID_HDMI_DC_48) {
>  		dc_bpc = 16;
>  		info->edid_hdmi_rgb444_dc_modes |= DRM_EDID_HDMI_DC_48;
>  		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI sink does deep color 48.\n",
> @@ -6333,7 +6333,7 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>  	info->bpc = dc_bpc;
>  
>  	/* YCRCB444 is optional according to spec. */
> -	if (hdmi[6] & DRM_EDID_HDMI_DC_Y444) {
> +	if (db->data[6] & DRM_EDID_HDMI_DC_Y444) {
>  		info->edid_hdmi_ycbcr444_dc_modes = info->edid_hdmi_rgb444_dc_modes;
>  		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI sink does YCRCB444 in deep color.\n",
>  			    connector->base.id, connector->name);
> @@ -6343,7 +6343,7 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>  	 * Spec says that if any deep color mode is supported at all,
>  	 * then deep color 36 bit must be supported.
>  	 */
> -	if (!(hdmi[6] & DRM_EDID_HDMI_DC_36)) {
> +	if (!(db->data[6] & DRM_EDID_HDMI_DC_36)) {
>  		drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI sink should do DC_36, but does not!\n",
>  			    connector->base.id, connector->name);
>  	}
> @@ -6351,19 +6351,19 @@ static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
>  
>  /* HDMI Vendor-Specific Data Block (HDMI VSDB, H14b-VSDB) */
>  static void
> -drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db)
> +drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const struct cea_db *db)
>  {
>  	struct drm_display_info *info = &connector->display_info;
>  	u8 len = cea_db_payload_len(db);
>  
>  	info->is_hdmi = true;
>  
> -	info->source_physical_address = (db[4] << 8) | db[5];
> +	info->source_physical_address = (db->data[4] << 8) | db->data[5];
>  
>  	if (len >= 6)
> -		info->dvi_dual = db[6] & 1;
> +		info->dvi_dual = db->data[6] & 1;
>  	if (len >= 7)
> -		info->max_tmds_clock = db[7] * 5000;
> +		info->max_tmds_clock = db->data[7] * 5000;
>  
>  	/*
>  	 * Try to infer whether the sink supports HDMI infoframes.
> @@ -6371,7 +6371,7 @@ drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db)
>  	 * HDMI infoframe support was first added in HDMI 1.4. Assume the sink
>  	 * supports infoframes if HDMI_Video_present is set.
>  	 */
> -	if (len >= 8 && db[8] & BIT(5))
> +	if (len >= 8 && db->data[8] & BIT(5))
>  		info->has_hdmi_infoframe = true;
>  
>  	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] HDMI: DVI dual %d, max TMDS clock %d kHz\n",
> @@ -6443,7 +6443,7 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>  		const u8 *data = (const u8 *)db;
>  
>  		if (cea_db_is_hdmi_vsdb(db))
> -			drm_parse_hdmi_vsdb_video(connector, data);
> +			drm_parse_hdmi_vsdb_video(connector, db);
>  		else if (cea_db_is_hdmi_forum_vsdb(db) ||
>  			 cea_db_is_hdmi_forum_scdb(db))
>  			drm_parse_hdmi_forum_scds(connector, data);

-- 
Jani Nikula, Intel