[PATCH 03/11] drm: parse ycbcr 420 vdb block

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

From: Jose Abreu <jose.abreu@synopsys.com>

HDMI 2.0 spec adds support for ycbcr420 subsampled output.
CEA-861-F adds two new blocks in EDID, to provide information about
sink's support for ycbcr420 output.

These new blocks are:
- ycbcr420 video data (vdb) block: video modes which can be supported
  only in ycbcr420 output mode.
- ycbcr420 video capability data (vcb) block: video modes which can be
  support in ycbcr420 output mode also (along with RGB, YCBCR 444/422 etc)

This patch adds parsing and handling of ycbcr420-vdb in the DRM
layer.

This patch is a modified version of Jose's RFC patch:
https://patchwork.kernel.org/patch/9492327/
so the authorship is maintained.

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
---
 drivers/gpu/drm/drm_edid.c  | 54 +++++++++++++++++++++++++++++++++++++++++++--
 drivers/gpu/drm/drm_modes.c | 10 +++++++--
 include/drm/drm_connector.h |  1 +
 include/uapi/drm/drm_mode.h |  6 +++++
 4 files changed, 67 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 8d98687..64d8e2e 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2777,6 +2777,7 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
 #define VENDOR_BLOCK    0x03
 #define SPEAKER_BLOCK	0x04
 #define VIDEO_CAPABILITY_BLOCK	0x07
+#define VIDEO_DATA_BLOCK_420	0x0E
 #define EDID_BASIC_AUDIO	(1 << 6)
 #define EDID_CEA_YCRCB444	(1 << 5)
 #define EDID_CEA_YCRCB422	(1 << 4)
@@ -3278,6 +3279,32 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
 	return modes;
 }
 
+/* Modes which can be supported in ycbcr 420 format only */
+static int do_420_vdb_modes(struct drm_connector *connector, const u8 *svds,
+		u8 svds_len)
+{
+	int modes = 0, i;
+	struct drm_device *dev = connector->dev;
+	struct drm_display_mode *newmode;
+	struct drm_display_info *info = &connector->display_info;
+
+	for (i = 0; i < svds_len; i++) {
+		u8 vic = svds[i] & 0x7f;
+
+		newmode = drm_mode_duplicate(dev, &edid_cea_modes[vic]);
+		if (!newmode)
+			break;
+
+		newmode->flags |= DRM_MODE_FLAG_420_ONLY;
+		drm_mode_probed_add(connector, newmode);
+		modes++;
+	}
+
+	if (modes > 0)
+		info->color_formats |= DRM_COLOR_FORMAT_YCRCB420;
+	return modes;
+}
+
 /*
  * do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
  * @connector: connector corresponding to the HDMI sink
@@ -3434,6 +3461,12 @@ cea_db_tag(const u8 *db)
 }
 
 static int
+cea_db_extended_tag(const u8 *db)
+{
+	return db[1];
+}
+
+static int
 cea_revision(const u8 *cea)
 {
 	return cea[1];
@@ -3482,6 +3515,17 @@ static bool cea_db_is_hdmi_forum_vsdb(const u8 *db)
 	return oui == HDMI_FORUM_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;
+}
+
 #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)
 
@@ -3507,10 +3551,16 @@ 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_hdmi_vdb420(db)) {
+				const u8 *vdb420 = &db[2];
+				u8 vdb420_len = dbl - 1;
+
+				/* Add 4:2:0(only) modes present in EDID */
+				modes += do_420_vdb_modes(connector, vdb420,
+							  vdb420_len);
 			}
 		}
 	}
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index f2493b9..10432f3 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -987,6 +987,10 @@ 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);
@@ -1005,6 +1009,9 @@ EXPORT_SYMBOL(drm_mode_equal_no_clocks);
 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 &&
@@ -1015,8 +1022,7 @@ 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/drm/drm_connector.h b/include/drm/drm_connector.h
index 4eeda12..cef76b2 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -199,6 +199,7 @@ 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<<2)
 
 	/**
 	 * @color_formats: HDMI Color formats, selects between RGB and YCrCb
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 8c67fc0..1e74d8e 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -84,6 +84,12 @@ extern "C" {
 #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<<23)
+#define  DRM_MODE_FLAG_420			(1<<23)
+#define  DRM_MODE_FLAG_420_ONLY			(1<<24)
 
 /* Picture aspect ratio options */
 #define DRM_MODE_PICTURE_ASPECT_NONE		0
-- 
2.7.4

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