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Subject[RFC] drm: Parse HDMI 2.0 YCbCr 4:2:0 VDB and VCB
Date
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@synopsys.com>
Cc: Carlos Palminha <palminha@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.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]);
+ 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
--
1.9.1

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