Re: [RESEND-CI v4 04/15] drm/edid: parse YCBCR 420 videomodes from EDID

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards

Shashank


On 6/27/2017 5:22 PM, Ville Syrjälä wrote:
> On Wed, Jun 21, 2017 at 04:04:02PM +0530, Shashank Sharma wrote:
>> HDMI 2.0 spec adds support for YCBCR420 sub-sampled output.
>> CEA-861-F adds two new blocks in EDID's CEA extension blocks,
>> to provide information about sink's YCBCR420 output capabilities.
>>
>> These blocks are:
>>
>> - YCBCR420vdb(YCBCR 420 video data block):
>> This block contains VICs of video modes, which can be sopported only
>> in YCBCR420 output mode (Not in RGB/YCBCR444/422. Its like a normal
>> SVD block, valid for YCBCR420 modes only.
>>
>> - YCBCR420cmdb(YCBCR 420 capability map data block):
>> This block gives information about video modes which can support
>> YCBCR420 output mode also (along with RGB,YCBCR444/422 etc) This
>> block contains a bitmap index of normal svd videomodes, which can
>> support YCBCR420 output too.
>> So if bit 0 from first vcb byte is set, first video mode in the svd
>> list can support YCBCR420 output too. Bit 1 means second video mode
>> from svd list can support YCBCR420 output too, and so on.
>>
>> This patch adds two bitmaps in display's hdmi_info structure, one each
>> for VCB and VDB modes. If the source is HDMI 2.0 capable, this patch
>> adds:
>> - VDB modes (YCBCR 420 only modes) in connector's mode list, also makes
>>    an entry in the vdb_bitmap per vic.
>> - VCB modes (YCBCR 420 also modes) only entry in the vcb_bitmap.
>>
>> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
>> Cc: Jose Abreu <joabreu@synopsys.com>
>> Cc: Emil Velikov <emil.l.velikov@gmail.com>
>>
>> V2: Addressed
>>      Review comments from Emil:
>>      - Use 1ULL<<i instead of 1<<i to make sure the output is 64bit.
>>      - Use the suggested method for updating dbmap.
>>      - Add documentation for YCBCR420_vcb_map to fix kbuild warning.
>>
>>      Review comments from Ville:
>>      - Do not expose the YCBCR420 flags in uabi layer, keep it internal.
>>      - Save a map of YCBCR420 modes for future reference.
>>      - Check db length before trying to parse extended tag.
>>      - Add a warning if there are > 64 modes in capability map block.
>>      - Use y420cmdb in function names and macros while dealing with vcb
>>        to be aligned with spec.
>>      - Move the display information parsing block ahead of mode parsing
>>        blocks.
>>
>> V3: Addressed design/review comments from Ville
>>      - Do not add flags in video modes, else we have to expose them to user
>>      - There should not be a UABI change, and kernel should detect the
>>        choice of the output based on type of mode, and the bitmaps.
>>      - Use standard bitops from kernel bitmap header, instead of calculating
>>        bit positions manually.
>>
>> V4: Addressed review comments from Ville:
>>      - s/ycbcr_420_vdb/y420vdb
>>      - s/ycbcr_420_vcb/y420cmdb
>>      - Be less verbose on description of do_y420vdb_modes
>>      - Move newmode variable in the loop scope.
>>      - Use svd_to_vic() to get a VIC, instead of 0x7f
>>      - Remove bitmap description for CMDB modes & VDB modes
>>      - Dont add connector->ycbcr_420_allowed check for cmdb modes
>>      - Remove 'len' variable, in is_y420cmdb function, which is used
>>        only once
>>      - Add length check in is_y420vdb function
>>      - Remove unnecessary if (!db) check in function parse_y420cmdb_bitmap
>>      - Do not add print about YCBCR 420 modes
>>      - Fix indentation in few places
>>      - Move ycbcr420_dc_modes in next patch, where its used
>>      - Add a separate patch for movement of drm_add_display_info()
>>
>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/drm_edid.c  | 157 +++++++++++++++++++++++++++++++++++++++++++-
>>   include/drm/drm_connector.h |  20 ++++++
>>   2 files changed, 174 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index e2d1b30..8c7e73b 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -2781,7 +2781,9 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
>>   #define VIDEO_BLOCK     0x02
>>   #define VENDOR_BLOCK    0x03
>>   #define SPEAKER_BLOCK	0x04
>> -#define VIDEO_CAPABILITY_BLOCK	0x07
>> +#define VIDEO_CAPABILITY_BLOCK 0x07
>> +#define VIDEO_DATA_BLOCK_420	0x0E
>> +#define VIDEO_CAP_BLOCK_Y420CMDB 0x0F
>>   #define EDID_BASIC_AUDIO	(1 << 6)
>>   #define EDID_CEA_YCRCB444	(1 << 5)
>>   #define EDID_CEA_YCRCB422	(1 << 4)
>> @@ -3153,15 +3155,79 @@ drm_display_mode_from_vic_index(struct drm_connector *connector,
>>   	return newmode;
>>   }
>>   
>> +/*
>> + * do_y420vdb_modes - Parse YCBCR 420 only modes
>> + * @connector: connector corresponding to the HDMI sink
>> + * @svds: start of the data block of CEA YCBCR 420 VDB
>> + * @len: length of the CEA YCBCR 420 VDB
>> + *
>> + * Parse the CEA-861-F YCBCR 420 Video Data Block (Y420VDB)
>> + * which contains modes which can be supported in YCBCR 420
>> + * output format only.
>> + */
>> +static int do_y420vdb_modes(struct drm_connector *connector,
>> +				   const u8 *svds, u8 svds_len)
>> +{
>> +	int modes = 0, i;
>> +	struct drm_device *dev = connector->dev;
>> +	struct drm_display_info *info = &connector->display_info;
>> +	struct drm_hdmi_info *hdmi = &info->hdmi;
>> +
>> +	for (i = 0; i < svds_len; i++) {
>> +		u8 vic = svd_to_vic(svds[i]);
>> +		struct drm_display_mode *newmode;
>> +
>> +		newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
>> +		if (!newmode)
>> +			break;
>> +		bitmap_set(hdmi->y420_vdb_modes, vic, 1);
>> +		drm_mode_probed_add(connector, newmode);
>> +		modes++;
>> +	}
>> +
>> +	if (modes > 0)
>> +		info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
>> +	return modes;
>> +}
>> +
>> +/*
>> + * drm_add_cmdb_modes - Add a YCBCR 420 mode into bitmap
>> + * @connector: connector corresponding to the HDMI sink
>> + * @vic: CEA vic for the video mode to be added in the map
>> + *
>> + * Makes an entry for a videomode in the YCBCR 420 bitmap
>> + */
>> +static void
>> +drm_add_cmdb_modes(struct drm_connector *connector, u8 svd)
>> +{
>> +	u8 vic = svd_to_vic(svd);
>> +	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
>> +
>> +	bitmap_set(hdmi->y420_cmdb_modes, vic, 1);
>> +}
>> +
>>   static int
>>   do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
>>   {
>>   	int i, modes = 0;
>> +	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
>>   
>>   	for (i = 0; i < len; i++) {
>>   		struct drm_display_mode *mode;
>>   		mode = drm_display_mode_from_vic_index(connector, db, len, i);
>>   		if (mode) {
>> +			/*
>> +			 * YCBCR420 capability block contains a bitmap which
>> +			 * gives the index of CEA modes from CEA VDB, which
>> +			 * can support YCBCR 420 sampling output also (apart
>> +			 * from RGB/YCBCR444 etc).
>> +			 * For example, if the bit 0 in bitmap is set,
>> +			 * first mode in VDB can support YCBCR420 output too.
>> +			 * Add YCBCR420 modes only if sink is HDMI 2.0 capable.
>> +			 */
>> +			if (test_bit(i, &hdmi->y420_cmdb_map))
>> +				drm_add_cmdb_modes(connector, db[i]);
>> +
>>   			drm_mode_probed_add(connector, mode);
>>   			modes++;
>>   		}
>> @@ -3437,6 +3503,12 @@ do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len,
>>   }
>>   
>>   static int
>> +cea_db_extended_tag(const u8 *db)
>> +{
>> +	return db[1];
>> +}
>> +
>> +static int
>>   cea_db_payload_len(const u8 *db)
>>   {
>>   	return db[0] & 0x1f;
>> @@ -3497,9 +3569,78 @@ static bool cea_db_is_hdmi_forum_vsdb(const u8 *db)
>>   	return oui == HDMI_FORUM_IEEE_OUI;
>>   }
>>   
>> +static bool cea_db_is_y420cmdb(const u8 *db)
>> +{
>> +
>> +	if (cea_db_tag(db) != VIDEO_CAPABILITY_BLOCK)
> Still would like to see that patch to clean up the current extended tag
> usage...
Yep, its on the way, running a bit loaded.
>> +		return false;
>> +
>> +	if (!cea_db_payload_len(db))
>> +		return false;
>> +
>> +	if (cea_db_extended_tag(db) != VIDEO_CAP_BLOCK_Y420CMDB)
>> +		return false;
>> +
>> +	return true;
>> +}
>> +
>> +static bool cea_db_is_y420vdb(const u8 *db)
>> +{
>> +	if (cea_db_tag(db) != VIDEO_CAPABILITY_BLOCK)
>> +		return false;
>> +
>> +	if (!cea_db_payload_len(db))
>> +		return false;
>> +
>> +	if (cea_db_extended_tag(db) != VIDEO_DATA_BLOCK_420)
>> +		return false;
>> +
>> +	return true;
>> +}
>> +
>>   #define for_each_cea_db(cea, i, start, end) \
>>   	for ((i) = (start); (i) < (end) && (i) + cea_db_payload_len(&(cea)[(i)]) < (end); (i) += cea_db_payload_len(&(cea)[(i)]) + 1)
>>   
>> +static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
>> +				     const u8 *db)
>> +{
>> +	struct drm_display_info *info = &connector->display_info;
>> +	struct drm_hdmi_info *hdmi = &info->hdmi;
>> +	u8 map_len = cea_db_payload_len(db) - 1;
>> +	u8 count;
>> +	u64 map = 0;
>> +
>> +	if (map_len == 0) {
>> +		/* All CEA modes support ycbcr420 sampling also.*/
>> +		hdmi->y420_cmdb_map = U64_MAX;
>> +		info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
>> +		return;
>> +	}
>> +
>> +	/*
>> +	 * This map indicates which of the existing CEA block modes
>> +	 * from VDB can support YCBCR420 output too. So if bit=0 is
>> +	 * set, first mode from VDB can support YCBCR420 output too.
>> +	 * We will parse and keep this map, before parsing VDB itself
>> +	 * to avoid going through the same block again and again.
>> +	 *
>> +	 * Spec is not clear about max possible size of this block.
>> +	 * Clamping max bitmap block size at 8 bytes. Every byte can
>> +	 * address 8 CEA modes, in this way this map can address
>> +	 * 8*8 = first 64 SVDs.
>> +	 */
>> +	if (WARN_ON_ONCE(map_len > 8))
>> +		map_len = 8;
>> +
>> +	for (count = 0; count < map_len; count++)
>> +		map |= (u64)db[2 + count] << (8 * count);
>> +
>> +	if (map)
>> +		info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
>> +
>> +	hdmi->y420_cmdb_map = map;
>> +}
>> +
>>   static int
>>   add_cea_modes(struct drm_connector *connector, struct edid *edid)
>>   {
>> @@ -3522,10 +3663,17 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
>>   				video = db + 1;
>>   				video_len = dbl;
>>   				modes += do_cea_modes(connector, video, dbl);
>> -			}
>> -			else if (cea_db_is_hdmi_vsdb(db)) {
>> +			} else if (cea_db_is_hdmi_vsdb(db)) {
>>   				hdmi = db;
>>   				hdmi_len = dbl;
>> +			} else if (cea_db_is_y420vdb(db) &&
>> +				   connector->ycbcr_420_allowed) {
>> +				const u8 *vdb420 = &db[2];
>> +
>> +				/* Add 4:2:0(only) modes present in EDID */
>> +				modes += do_y420vdb_modes(connector,
>> +							  vdb420,
>> +							  dbl - 1);
>>   			}
>>   		}
>>   	}
>> @@ -4206,6 +4354,8 @@ 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_y420cmdb(db))
>> +			drm_parse_y420cmdb_bitmap(connector, db);
>>   	}
>>   }
>>   
>> @@ -4460,6 +4610,7 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
>>   	num_modes += add_cea_modes(connector, edid);
>>   	num_modes += add_alternate_cea_modes(connector, edid);
>>   	num_modes += add_displayid_detailed_modes(connector, edid);
>> +
>>   	if (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF)
>>   		num_modes += add_inferred_modes(connector, edid);
>>   
>> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
>> index 7493fd3..ce2212d 100644
>> --- a/include/drm/drm_connector.h
>> +++ b/include/drm/drm_connector.h
>> @@ -137,6 +137,25 @@ struct drm_scdc {
>>   struct drm_hdmi_info {
>>   	/** @scdc: sink's scdc support and capabilities */
>>   	struct drm_scdc scdc;
>> +
>> +	/**
>> +	 * @y420_vdb_modes: bitmap of modes which can support ycbcr420
>> +	 * output only (not normal RGB/YCBCR444/422 outputs). There are total
>> +	 * 107 VICs defined by CEA-861-F spec, so the size is 128 bits to map
>> +	 * upto 128 VICs;
>> +	 */
>> +	unsigned long y420_vdb_modes[BITS_TO_LONGS(128)];
>> +
>> +	/**
>> +	 * @y420_cmdb_modes: bitmap of modes which can support ycbcr420
>> +	 * output also, along with normal HDMI outputs. There are total 107
>> +	 * VICs defined by CEA-861-F spec, so the size is 128 bits to map upto
>> +	 * 128 VICs;
>> +	 */
>> +	unsigned long y420_cmdb_modes[BITS_TO_LONGS(128)];
>> +
>> +	/** @y420_cmdb_map: bitmap of SVD index, to extraxt vcb modes */
>> +	unsigned long y420_cmdb_map;
> u64, otherwise it's busted on 32bit machines.
Got it.
>
> Mostl this looks pretty good. I think the main problem is the lack of
> mode validation that would reject the 4:2:0 only modes if not supported
> by the driver/device. I guess that's in a later patch?
Yep, its the next patch in the series.
>   If so we need to
> reorder the series a bit to avoid regeressions.
That patch uses parameters added in this patch, to detect the 4:2:0 only 
modes. So cant make it before this patch.
Let me see what best can I do on the reordering.

- Shashank
>>   };
>>   
>>   /**
>> @@ -200,6 +219,7 @@ struct drm_display_info {
>>   #define DRM_COLOR_FORMAT_RGB444		(1<<0)
>>   #define DRM_COLOR_FORMAT_YCRCB444	(1<<1)
>>   #define DRM_COLOR_FORMAT_YCRCB422	(1<<2)
>> +#define DRM_COLOR_FORMAT_YCRCB420	(1<<3)
>>   
>>   	/**
>>   	 * @color_formats: HDMI Color formats, selects between RGB and YCrCb
>> -- 
>> 2.7.4

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