[v4 5/5] drm/edid: check for HF-SCDB block

[Lee, Shawn C]

On Thursday, March 10, 2022 6:50 PM, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
>On Wed, Mar 02, 2022 at 05:35:11PM +0800, Lee Shawn C wrote:
>> Find HF-SCDB information in CEA extensions block. And retrieve 
>> Max_TMDS_Character_Rate that support by sink device.
>> 
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
>> Cc: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> Signed-off-by: Lee Shawn C <shawn.c.lee at intel.com>
>> ---
>>  drivers/gpu/drm/drm_edid.c | 36 ++++++++++++++++++++++++++++++++++++
>>  1 file changed, 36 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c 
>> index 2b8ddc956ce2..d6b48c543c23 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -3350,6 +3350,7 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
>>  #define EXT_VIDEO_DATA_BLOCK_420	0x0E
>>  #define EXT_VIDEO_CAP_BLOCK_Y420CMDB	0x0F
>>  #define EXT_VIDEO_HF_EEODB_DATA_BLOCK	0x78
>> +#define EXT_VIDEO_HF_SCDB_DATA_BLOCK	0x79
>>  #define EDID_BASIC_AUDIO	(1 << 6)
>>  #define EDID_CEA_YCRCB444	(1 << 5)
>>  #define EDID_CEA_YCRCB422	(1 << 4)
>> @@ -4277,6 +4278,20 @@ static bool cea_db_is_vcdb(const u8 *db)
>>  	return true;
>>  }
>>  
>> +static bool cea_db_is_hf_scdb(const u8 *db) {
>> +	if (cea_db_tag(db) != USE_EXTENDED_TAG)
>> +		return false;
>> +
>> +	if (cea_db_payload_len(db) < 7)
>> +		return false;
>> +
>> +	if (cea_db_extended_tag(db) != EXT_VIDEO_HF_SCDB_DATA_BLOCK)
>> +		return false;
>> +
>> +	return true;
>> +}
>> +
>>  static bool cea_db_is_y420cmdb(const u8 *db)  {
>>  	if (cea_db_tag(db) != USE_EXTENDED_TAG) @@ -4987,6 +5002,25 @@ 
>> static void drm_parse_vcdb(struct drm_connector *connector, const u8 *db)
>>  		info->rgb_quant_range_selectable = true;  }
>>  
>> +static void drm_parse_hf_scdb(struct drm_connector *connector, const 
>> +u8 *db) {
>> +	struct drm_display_info *info = &connector->display_info;
>> +	u32 max_tmds_clock;
>> +
>> +	DRM_DEBUG_KMS("HF-SCDB version 0x%02x\n", db[4]);
>> +
>> +	max_tmds_clock = db[5] * 5000;
>> +	if (info->max_tmds_clock < max_tmds_clock) {
>> +		info->max_tmds_clock = max_tmds_clock;
>> +		DRM_DEBUG_KMS("HF-SCDB: max TMDS clock %d kHz\n",
>> +			      info->max_tmds_clock);
>> +	}
>> +
>> +	/*
>> +	 * ToDo: Parse the remaining SCDB data if needed
>> +	 */
>
>If I'm reading the spec right this block should contain the exact same stuff as the HF-VSDB. We should reuse the same code for parsing both.
>

Yes, you are right! HF-SCDB contain the same SCDS data packet as VSDB. I will fix it later.

Best regards,
Shawn

>> +}
>> +
>>  static
>>  void drm_get_max_frl_rate(int max_frl_rate, u8 *max_lanes, u8 
>> *max_rate_per_lane)  { @@ -5282,6 +5316,8 @@ static void 
>> drm_parse_cea_ext(struct drm_connector *connector,
>>  			drm_parse_y420cmdb_bitmap(connector, db);
>>  		if (cea_db_is_vcdb(db))
>>  			drm_parse_vcdb(connector, db);
>> +		if (cea_db_is_hf_scdb(db))
>> +			drm_parse_hf_scdb(connector, db);
>>  		if (cea_db_is_hdmi_hdr_metadata_block(db))
>>  			drm_parse_hdr_metadata_block(connector, db);
>>  	}
>> --
>> 2.17.1
>
>--
>Ville Syrjälä
>Intel
>