Message-ID: <a3d50712-8f57-f70d-3e01-88037e657e5d@intel.com>
Date:   Mon, 9 Jan 2017 10:52:17 +0530
From:   "Sharma, Shashank" <shashank.sharma@...el.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Jose.Abreu@...opsys.com, daniel.vetter@...el.com,
        linux-kernel@...r.kernel.org, ville.syrjala@...ux.intel.com,
        shashidhar.hiremath@...el.com, indranil.mukherjee@...el.com
Subject: Re: [RFC] drm: Parse HDMI 2.0 YCbCr 4:2:0 VDB and VCB

Regards

Shashank


On 12/30/2016 10:23 PM, Jose Abreu wrote:
> HDMI 2.0 introduces a new sampling mode called YCbCr 4:2:0.
> According to the spec the EDID may contain two blocks that
> signal this sampling mode:
> 	- YCbCr 4:2:0 Video Data Block
> 	- YCbCr 4:2:0 Video Capability Map Data Block
>
> The video data block contains the list of vic's were
> only YCbCr 4:2:0 sampling mode shall be used while the
> video capability map data block contains a mask were
> YCbCr 4:2:0 sampling mode may be used.
>
> This RFC patch adds support for parsing these two new blocks
> and introduces new flags to signal the drivers if the
> mode is 4:2:0'only or 4:2:0'able.
>
> The reason this is still a RFC is because there is no
> reference in kernel for this new sampling mode (specially in
> AVI infoframe part), so, I was hoping to hear some feedback
> first.
>
> Tested in a HDMI 2.0 compliance scenario.
>
> Signed-off-by: Jose Abreu <joabreu@...opsys.com>
> Cc: Carlos Palminha <palminha@...opsys.com>
> Cc: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Sean Paul <seanpaul@...omium.org>
> Cc: David Airlie <airlied@...ux.ie>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-kernel@...r.kernel.org
> ---
>   drivers/gpu/drm/drm_edid.c  | 139 +++++++++++++++++++++++++++++++++++++++++++-
>   drivers/gpu/drm/drm_modes.c |  10 +++-
>   include/uapi/drm/drm_mode.h |   6 ++
>   3 files changed, 151 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 67d6a73..6ce1a38 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2549,6 +2549,8 @@ static int drm_cvt_modes(struct drm_connector *connector,
>   #define VENDOR_BLOCK    0x03
>   #define SPEAKER_BLOCK	0x04
>   #define VIDEO_CAPABILITY_BLOCK	0x07
> +#define VIDEO_DATA_BLOCK_420	0x0E
> +#define VIDEO_CAP_BLOCK_420	0x0F
>   #define EDID_BASIC_AUDIO	(1 << 6)
>   #define EDID_CEA_YCRCB444	(1 << 5)
>   #define EDID_CEA_YCRCB422	(1 << 4)
> @@ -3050,6 +3052,98 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
>   	return modes;
>   }
>   
> +static int add_420_mode(struct drm_connector *connector, u8 vic)
> +{
> +	struct drm_device *dev = connector->dev;
> +	struct drm_display_mode *newmode;
> +
> +	if (!drm_valid_cea_vic(vic))
> +		return 0;
> +
> +	newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
Sorry to start the review late, I missed this mail chain. It would be 
great if you can please keep me in CC for this chain.

Practically, YUV420 modes are being used for 4k and UHD video modes. Now 
here, when we want to
add these modes from edid_cea_db, using the VIC index, we should have 
full list of cea_modes from 1 - 107
Particularly 93-107 ( which is for new 38x21 and 40x21 modes, added in 
CEA-861-F). right now, edid_cea_modes
cant index 4k modes, so practically this this patch series will do 
nothing (even though its doing everything right)

To handle this scenario, I had added a patch series 
https://patchwork.freedesktop.org/patch/119627/
(complete the cea modedb (VIC=65 onwards)) Now, this patch series had 
dependency on new aspect ratios
being added in CEA-861-F which I tried to add in series 
(https://patchwork.freedesktop.org/patch/116095/)
Which was added and later reverted by Ville 
(https://patchwork.freedesktop.org/patch/119808/).

In short, the method/sequence for effective development would be:
- Add aspect ratio support in DRM
- Add HDMI 2.0 (CEA-861-F) aspect ratios 
(https://patchwork.freedesktop.org/patch/116095/)
- Complete edid_cea_modes, adding new modes as per 4k VICs 
(https://patchwork.freedesktop.org/patch/119627/ )
- Parse these modes from 420_vdb and 420_vcb using edid_cea_modes db[]  
(This patch series)

And that we should re-prioritize the aspect ratio handling to target YUV 
420 handling from CEA blocks.
Shashank
> +	if (!newmode)
> +		return 0;
> +
> +	newmode->flags |= DRM_MODE_FLAG_420_ONLY;
> +	drm_mode_probed_add(connector, newmode);
> +
> +	return 1;
> +}
> +
> +static int add_420_vdb_modes(struct drm_connector *connector, const u8 *svds,
> +		u8 svds_len)
> +{
> +	int modes = 0, i;
> +
> +	for (i = 0; i < svds_len; i++)
> +		modes += add_420_mode(connector, svds[i]);
> +
> +	return modes;
> +}
> +
> +static int add_420_vcb_modes(struct drm_connector *connector, const u8 *svds,
> +		u8 svds_len, const u8 *video_db, u8 video_len)
> +{
> +	struct drm_display_mode *newmode = NULL;
> +	int modes = 0, i, j;
> +
> +	for (i = 0; i < svds_len; i++) {
> +		u8 mask = svds[i];
> +		for (j = 0; j < 8; j++) {
> +			if (mask & (1 << j)) {
> +				newmode = drm_display_mode_from_vic_index(
> +						connector, video_db, video_len,
> +						i * 8 + j);
> +				if (newmode) {
> +					newmode->flags |= DRM_MODE_FLAG_420;
> +					drm_mode_probed_add(connector, newmode);
> +					modes++;
> +				}
> +			}
> +		}
> +	}
> +
> +	return modes;
> +}
> +
> +static int add_420_vcb_modes_all(struct drm_connector *connector,
> +		const u8 *video_db, u8 video_len)
> +{
> +	struct drm_display_mode *newmode = NULL;
> +	int modes = 0, i;
> +
> +	for (i = 0; i < video_len; i++) {
> +		newmode = drm_display_mode_from_vic_index(connector, video_db,
> +				video_len, i);
> +		if (newmode) {
> +			newmode->flags |= DRM_MODE_FLAG_420;
> +			drm_mode_probed_add(connector, newmode);
> +			modes++;
> +		}
> +	}
> +
> +	return modes;
> +}
> +
> +static int do_hdmi_420_modes(struct drm_connector *connector, const u8 *vdb,
> +		u8 vdb_len, const u8 *vcb, u8 vcb_len, const u8 *video_db,
> +		u8 video_len)
> +{
> +	int modes = 0;
> +
> +	if (vdb && (vdb_len > 1)) /* Add 4:2:0 modes present in EDID */
> +		modes += add_420_vdb_modes(connector, &vdb[2], vdb_len - 1);
> +
> +	if (vcb && (vcb_len > 1)) /* Parse bit mask of supported modes */
> +		modes += add_420_vcb_modes(connector, &vcb[2], vcb_len - 1,
> +				video_db, video_len);
> +	else if (vcb) /* All modes support 4:2:0 mode */
> +		modes += add_420_vcb_modes_all(connector, video_db, video_len);
> +
> +	DRM_DEBUG("added %d 4:2:0 modes\n", modes);
> +	return modes;
> +}
> +
>   /*
>    * do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
>    * @connector: connector corresponding to the HDMI sink
> @@ -3206,6 +3300,12 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
>   }
>   
>   static int
> +cea_db_extended_tag(const u8 *db)
> +{
> +	return db[1];
> +}
> +
> +static int
>   cea_revision(const u8 *cea)
>   {
>   	return cea[1];
> @@ -3239,6 +3339,28 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db)
>   	return hdmi_id == HDMI_IEEE_OUI;
>   }
>   
> +static bool cea_db_is_hdmi_vdb420(const u8 *db)
> +{
> +	if (cea_db_tag(db) != VIDEO_CAPABILITY_BLOCK)
> +		return false;
> +
> +	if (cea_db_extended_tag(db) != VIDEO_DATA_BLOCK_420)
> +		return false;
> +
> +	return true;
> +}
> +
> +static bool cea_db_is_hdmi_vcb420(const u8 *db)
> +{
> +	if (cea_db_tag(db) != VIDEO_CAPABILITY_BLOCK)
> +		return false;
> +
> +	if (cea_db_extended_tag(db) != VIDEO_CAP_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)
>   
> @@ -3246,8 +3368,9 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db)
>   add_cea_modes(struct drm_connector *connector, struct edid *edid)
>   {
>   	const u8 *cea = drm_find_cea_extension(edid);
> -	const u8 *db, *hdmi = NULL, *video = NULL;
> -	u8 dbl, hdmi_len, video_len = 0;
> +	const u8 *db, *hdmi = NULL, *video = NULL, *vdb420 = NULL,
> +	      *vcb420 = NULL;
> +	u8 dbl, hdmi_len, video_len = 0, vdb420_len = 0, vcb420_len = 0;
>   	int modes = 0;
>   
>   	if (cea && cea_revision(cea) >= 3) {
> @@ -3269,6 +3392,14 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db)
>   				hdmi = db;
>   				hdmi_len = dbl;
>   			}
> +			else if (cea_db_is_hdmi_vdb420(db)) {
> +				vdb420 = db;
> +				vdb420_len = dbl;
> +			}
> +			else if (cea_db_is_hdmi_vcb420(db)) {
> +				vcb420 = db;
> +				vcb420_len = dbl;
> +			}
>   		}
>   	}
>   
> @@ -3280,6 +3411,10 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db)
>   		modes += do_hdmi_vsdb_modes(connector, hdmi, hdmi_len, video,
>   					    video_len);
>   
> +	if (vdb420 || vcb420)
> +		modes += do_hdmi_420_modes(connector, vdb420, vdb420_len,
> +				vcb420, vcb420_len, video, video_len);
> +
>   	return modes;
>   }
>   
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index ac6a352..53c65f6 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -967,6 +967,10 @@ bool drm_mode_equal_no_clocks(const struct drm_display_mode *mode1, const struct
>   	    (mode2->flags & DRM_MODE_FLAG_3D_MASK))
>   		return false;
>   
> +	if ((mode1->flags & DRM_MODE_FLAG_420_MASK) !=
> +	    (mode2->flags & DRM_MODE_FLAG_420_MASK))
> +		return false;
> +
>   	return drm_mode_equal_no_clocks_no_stereo(mode1, mode2);
>   }
>   EXPORT_SYMBOL(drm_mode_equal_no_clocks);
> @@ -985,6 +989,9 @@ bool drm_mode_equal_no_clocks(const struct drm_display_mode *mode1, const struct
>   bool drm_mode_equal_no_clocks_no_stereo(const struct drm_display_mode *mode1,
>   					const struct drm_display_mode *mode2)
>   {
> +	unsigned int flags_mask =
> +		~(DRM_MODE_FLAG_3D_MASK | DRM_MODE_FLAG_420_MASK);
> +
>   	if (mode1->hdisplay == mode2->hdisplay &&
>   	    mode1->hsync_start == mode2->hsync_start &&
>   	    mode1->hsync_end == mode2->hsync_end &&
> @@ -995,8 +1002,7 @@ bool drm_mode_equal_no_clocks_no_stereo(const struct drm_display_mode *mode1,
>   	    mode1->vsync_end == mode2->vsync_end &&
>   	    mode1->vtotal == mode2->vtotal &&
>   	    mode1->vscan == mode2->vscan &&
> -	    (mode1->flags & ~DRM_MODE_FLAG_3D_MASK) ==
> -	     (mode2->flags & ~DRM_MODE_FLAG_3D_MASK))
> +	    (mode1->flags & flags_mask) == (mode2->flags & flags_mask))
>   		return true;
>   
>   	return false;
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index ce7efe2..dc8e285 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -84,6 +84,12 @@
>   #define  DRM_MODE_FLAG_3D_L_DEPTH_GFX_GFX_DEPTH	(6<<14)
>   #define  DRM_MODE_FLAG_3D_TOP_AND_BOTTOM	(7<<14)
>   #define  DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF	(8<<14)
> +/*
> + * HDMI 2.0
> + */
> +#define DRM_MODE_FLAG_420_MASK			(0x03<<19)
> +#define  DRM_MODE_FLAG_420			(1<<19)
> +#define  DRM_MODE_FLAG_420_ONLY			(1<<20)
>   
>   /* Picture aspect ratio options */
>   #define DRM_MODE_PICTURE_ASPECT_NONE		0

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