Re: [PATCH v2 03/11] drm: parse ycbcr420 cmdb block

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

On Tue, May 30, 2017 at 05:43:42PM +0530, Shashank Sharma wrote:
> HDMI 2.0 spec adds support for ycbcr420 sub-sampled output.
> CEA-861-F adds two new blocks in EDID, to provide information
> about sink's support for ycbcr420 output.
> 
> One of these new blocks is: ycbcr420cmdb(ycbcr 420 capability
> map data block). This 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 2 means second video mode from svd
> list can support ycbcr420 output too, and so on.
> 
> This patch adds parsing and handling of ycbcr420-cmdb in the DRM layer.
> 
> 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.
> 
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c  | 118 ++++++++++++++++++++++++++++++++++++++++++--
>  include/drm/drm_connector.h |  12 +++++
>  2 files changed, 127 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index c3fa3a1..ce86528 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)
> @@ -3143,15 +3145,50 @@ drm_display_mode_from_vic_index(struct drm_connector *connector,
>  	return newmode;
>  }
>  
> +static void
> +drm_add_vcb_modes(struct drm_connector *connector, u8 vic)
> +{
> +	u32 *map;
> +	u8 index = 0;
> +	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
> +
> +	/* VICs are 1 to 127(107 defined till CEA-861-F) */
> +	vic &= 127;
> +
> +	/*
> +	 * ycbcr420_vcb_modes is a fix position 128 bit bitmap. This indicates
> +	 * support for ycbcr420 output per VIC. Arrangement is bit[n] indicates
> +	 * if vic[n+1] supports ycbcr420 output.
> +	 * ycbcr420_vcb_modes[0] = |VIC=32 |VIC=31 |............|VIC=2 |VIC=1 |
> +	 * ycbcr420_vcb_modes[1] = |VIC=64 |VIC=63 |............|VIC=34|VIC=33|
> +	 * ycbcr420_vcb_modes[2] = |VIC=96 |VIC=95 |............|VIC=66|VIC=65|
> +	 * ycbcr420_vcb_modes[3] = |VIC=128|VIC=127|............|VIC=34|VIC=97|
> +	 */
> +	map = &(hdmi->ycbcr420_vcb_modes[(vic - 1) / 32]);
> +	index = (vic - 1) % 32;
> +	*map |= (1 << index);

unsigned long whatever[BITS_TO_LONGS(nr)];

__set_bit(), test_bit(), etc.


> +}
> +
>  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;
> +	u64 hdmi_vcb_map = hdmi->ycbcr420_vcb_map;
>  
>  	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 such CEA modes in VDB, which can
> +			 * support ycbcr420 sampling output also.
> +			 * For example, if the bit 0 in bitmap is set,
> +			 * first mode in VDB can support ycbcr420 output too.
> +			 */
> +			if (hdmi_vcb_map & (1 << i))
> +				drm_add_vcb_modes(connector, db[i]);
>  			drm_mode_probed_add(connector, mode);
>  			modes++;
>  		}
> @@ -3427,6 +3464,12 @@ 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;
> @@ -3487,9 +3530,70 @@ 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)
> +{
> +	u8 len = cea_db_payload_len(db);
> +
> +	if (cea_db_tag(db) != VIDEO_CAPABILITY_BLOCK)
> +		return false;
> +
> +	if (!len)
> +		return false;
> +
> +	if (cea_db_extended_tag(db) != VIDEO_CAP_BLOCK_Y420CMDB)
> +		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 (!db)
> +		return;
> +
> +	if (map_len == 0) {
> +		/* All CEA modes support ycbcr420 sampling also.*/
> +		hdmi->ycbcr420_vcb_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) {
> +		DRM_DEBUG_KMS("Sink supports ycbcr 420\n");
> +		info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
> +	}
> +
> +	hdmi->ycbcr420_vcb_map = map;
> +}
> +
>  static int
>  add_cea_modes(struct drm_connector *connector, struct edid *edid)
>  {
> @@ -4196,6 +4300,8 @@ 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);
>  	}
>  }
>  
> @@ -4430,6 +4536,13 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
>  	quirks = edid_get_quirks(edid);
>  
>  	/*
> +	 * CEA-861-F adds ycbcr capability map block, for HDMI 2.0 sinks.
> +	 * To avoid multiple parsing of same block, lets get the sink info
> +	 * before parsing CEA modes.
> +	 */
> +	drm_add_display_info(connector, edid);
> +
> +	/*
>  	 * EDID spec says modes should be preferred in this order:
>  	 * - preferred detailed mode
>  	 * - other detailed modes from base block
> @@ -4450,14 +4563,13 @@ 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);
>  
>  	if (quirks & (EDID_QUIRK_PREFER_LARGE_60 | EDID_QUIRK_PREFER_LARGE_75))
>  		edid_fixup_preferred(connector, quirks);
>  
> -	drm_add_display_info(connector, edid);
> -
>  	if (quirks & EDID_QUIRK_FORCE_6BPC)
>  		connector->display_info.bpc = 6;
>  
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 2fe09c1..07b10ab 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -137,6 +137,17 @@ struct drm_scdc {
>  struct drm_hdmi_info {
>  	/** @scdc: sink's scdc support and capabilities */
>  	struct drm_scdc scdc;
> +
> +	/**
> +	 * @ycbcr420_vcb_modes: bitmap of modes which can support ycbcr420
> +	 * output also along with normal outputs. There are total 107 VICs
> +	 * defined by CEA-861-F spec, so the size is 128bits to map upto 128
> +	 * VICs;
> +	 */
> +	u32 ycbcr420_vcb_modes[4];
> +
> +	/** @ycbcr420_vcb_map: bitmap of SVD index, to extraxt vcb modes */
> +	u64 ycbcr420_vcb_map;
>  };
>  
>  /**
> @@ -200,6 +211,7 @@ 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

-- 
Ville Syrjälä
Intel OTC
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