Commit 2869f599 authored by Philipp Zabel's avatar Philipp Zabel Committed by Jani Nikula
Browse files

drm/edid: support Microsoft extension for HMDs and specialized monitors 

Add minimal support for parsing VSDBs documented in Microsoft's "EDID
extension for head-mounted and specialized monitors" [1]. The version
field and the desktop usage flag can be used to set the non_desktop
connector property.

[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/display/specialized-monitors-edid-extension



Tested with HPN-36C1 and LEN-B800.

Signed-off-by: default avatarPhilipp Zabel <philipp.zabel@gmail.com>
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220123101653.147333-1-philipp.zabel@gmail.com
parent b3bddb7a

drivers/gpu/drm/drm_edid.c

+34 −0
Original line number Diff line number Diff line
@@ -93,6 +93,8 @@ static int oui(u8 first, u8 second, u8 third) 
/* Non desktop display (i.e. HMD) */

#define EDID_QUIRK_NON_DESKTOP			(1 << 12)



#define MICROSOFT_IEEE_OUI	0xca125c



struct detailed_mode_closure {

	struct drm_connector *connector;

	struct edid *edid;
@@ -4222,6 +4224,17 @@ static bool cea_db_is_hdmi_forum_vsdb(const u8 *db) 
	return oui(db[3], db[2], db[1]) == HDMI_FORUM_IEEE_OUI;

}



static bool cea_db_is_microsoft_vsdb(const u8 *db)

{

	if (cea_db_tag(db) != VENDOR_BLOCK)

		return false;



	if (cea_db_payload_len(db) != 21)

		return false;



	return oui(db[3], db[2], db[1]) == MICROSOFT_IEEE_OUI;

}



static bool cea_db_is_vcdb(const u8 *db)

{

	if (cea_db_tag(db) != USE_EXTENDED_TAG)
@@ -5149,6 +5162,25 @@ drm_parse_hdmi_vsdb_video(struct drm_connector *connector, const u8 *db) 
	drm_parse_hdmi_deep_color_info(connector, db);

}



/*

 * See EDID extension for head-mounted and specialized monitors, specified at:

 * https://docs.microsoft.com/en-us/windows-hardware/drivers/display/specialized-monitors-edid-extension

 */

static void drm_parse_microsoft_vsdb(struct drm_connector *connector,

				     const u8 *db)

{

	struct drm_display_info *info = &connector->display_info;

	u8 version = db[4];

	bool desktop_usage = db[5] & BIT(6);



	/* Version 1 and 2 for HMDs, version 3 flags desktop usage explicitly */

	if (version == 1 || version == 2 || (version == 3 && !desktop_usage))

		info->non_desktop = true;



	drm_dbg_kms(connector->dev, "HMD or specialized display VSDB version %u: 0x%02x\n",

		    version, db[5]);

}



static void drm_parse_cea_ext(struct drm_connector *connector,

			      const struct edid *edid)

{
@@ -5179,6 +5211,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector, 
			drm_parse_hdmi_vsdb_video(connector, db);

		if (cea_db_is_hdmi_forum_vsdb(db))

			drm_parse_hdmi_forum_vsdb(connector, db);

		if (cea_db_is_microsoft_vsdb(db))

			drm_parse_microsoft_vsdb(connector, db);

		if (cea_db_is_y420cmdb(db))

			drm_parse_y420cmdb_bitmap(connector, db);

		if (cea_db_is_vcdb(db))