Re: [PATCH] drm: Parse Colorimetry data block from EDID

abhinavk@xxxxxxxxxxxxxx · Fri, 24 Jan 2020 12:43:07 -0800

Hi Ville

On 2020-01-24 06:36, Ville Syrjälä wrote:
On Thu, Jan 23, 2020 at 02:40:45PM -0800, Abhinav Kumar wrote:
From: Uma Shankar <uma.shankar@xxxxxxxxx>

CEA 861.3 spec adds colorimetry data block for HDMI.
Parsing the block to get the colorimetry data from
panel.

Why?
[Abhinav] The display driver for MSM chipsets still replies on the 
drm_edid.c for the parsing of
CEA extension blocks. Primarily we are using this information to know 
the supported colorspaces of the sink
(BT2020/DCI-P3) for use-cases such as HDR. The parts of the MSM display 
driver which use this block shall be posted
upstream a little bit later when our changes are ready to be posted.
Hence we would like drm_edid.c to be capable of parsing this block.
Thanks.



This was posted by Uma Shankar at
https://patchwork.kernel.org/patch/10861327/

Modified by Abhinav Kumar:
- Use macros to distinguish the bit fields for clarity

Signed-off-by: Uma Shankar <uma.shankar@xxxxxxxxx>
Signed-off-by: Abhinav Kumar <abhinavk@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_edid.c  | 54 
+++++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h |  3 +++
 include/drm/drm_edid.h      | 11 +++++++++
 3 files changed, 68 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 99769d6..148bfa4 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3136,6 +3136,7 @@ static int drm_cvt_modes(struct drm_connector 
*connector,
 #define VIDEO_BLOCK     0x02
 #define VENDOR_BLOCK    0x03
 #define SPEAKER_BLOCK	0x04
+#define COLORIMETRY_DATA_BLOCK		0x5
 #define HDR_STATIC_METADATA_BLOCK	0x6
 #define USE_EXTENDED_TAG 0x07
 #define EXT_VIDEO_CAPABILITY_BLOCK 0x00
@@ -4199,6 +4200,57 @@ static void 
fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
 	mode->clock = clock;
 }

+static bool cea_db_is_hdmi_colorimetry_data_block(const u8 *db)
+{
+	if (cea_db_tag(db) != USE_EXTENDED_TAG)
+		return false;
+
+	if (db[1] != COLORIMETRY_DATA_BLOCK)
+		return false;
+
+	if (cea_db_payload_len(db) < 2)
+		return false;
+
+	return true;
+}
+
+static void
+drm_parse_colorimetry_data_block(struct drm_connector *connector, 
const u8 *db)
+{
+	struct drm_hdmi_info *info = &connector->display_info.hdmi;
+
+	/* As per CEA 861-G spec */
+	/* Byte 3 Bit 0: xvYCC_601 */
+	if (db[2] & BIT(0))
+		info->colorimetry |= DRM_EDID_CLRMETRY_xvYCC_601;
+	/* Byte 3 Bit 1: xvYCC_709 */
+	if (db[2] & BIT(1))
+		info->colorimetry |= DRM_EDID_CLRMETRY_xvYCC_709;
+	/* Byte 3 Bit 2: sYCC_601 */
+	if (db[2] & BIT(2))
+		info->colorimetry |= DRM_EDID_CLRMETRY_sYCC_601;
+	/* Byte 3 Bit 3: ADBYCC_601 */
+	if (db[2] & BIT(3))
+		info->colorimetry |= DRM_EDID_CLRMETRY_ADBYCC_601;
+	/* Byte 3 Bit 4: ADB_RGB */
+	if (db[2] & BIT(4))
+		info->colorimetry |= DRM_EDID_CLRMETRY_ADB_RGB;
+	/* Byte 3 Bit 5: BT2020_CYCC */
+	if (db[2] & BIT(5))
+		info->colorimetry |= DRM_EDID_CLRMETRY_BT2020_CYCC;
+	/* Byte 3 Bit 6: BT2020_YCC */
+	if (db[2] & BIT(6))
+		info->colorimetry |= DRM_EDID_CLRMETRY_BT2020_YCC;
+	/* Byte 3 Bit 7: BT2020_RGB */
+	if (db[2] & BIT(7))
+		info->colorimetry |= DRM_EDID_CLRMETRY_BT2020_RGB;
+	/* Byte 4 Bit 7: DCI-P3 */
+	if (db[3] & BIT(7))
+		info->colorimetry |= DRM_EDID_CLRMETRY_DCI_P3;
+
+	DRM_DEBUG_KMS("Supported Colorimetry 0x%x\n", info->colorimetry);
+}
+
 static bool cea_db_is_hdmi_hdr_metadata_block(const u8 *db)
 {
 	if (cea_db_tag(db) != USE_EXTENDED_TAG)
@@ -4877,6 +4929,8 @@ static void drm_parse_cea_ext(struct 
drm_connector *connector,
 			drm_parse_vcdb(connector, db);
 		if (cea_db_is_hdmi_hdr_metadata_block(db))
 			drm_parse_hdr_metadata_block(connector, db);
+		if (cea_db_is_hdmi_colorimetry_data_block(db))
+			drm_parse_colorimetry_data_block(connector, db);
 	}
 }

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 2219109..a996ee3 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -207,6 +207,9 @@ struct drm_hdmi_info {

 	/** @y420_dc_modes: bitmap of deep color support index */
 	u8 y420_dc_modes;
+
+	/* @colorimetry: bitmap of supported colorimetry modes */
+	u16 colorimetry;
 };

 /**
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index f0b03d4..6168c1c 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -224,6 +224,17 @@ struct detailed_timing {
 				    DRM_EDID_YCBCR420_DC_36 | \
 				    DRM_EDID_YCBCR420_DC_30)

+/* Supported Colorimetry from colorimetry data block */
+#define DRM_EDID_CLRMETRY_xvYCC_601   (1 << 0)
+#define DRM_EDID_CLRMETRY_xvYCC_709   (1 << 1)
+#define DRM_EDID_CLRMETRY_sYCC_601    (1 << 2)
+#define DRM_EDID_CLRMETRY_ADBYCC_601  (1 << 3)
+#define DRM_EDID_CLRMETRY_ADB_RGB     (1 << 4)
+#define DRM_EDID_CLRMETRY_BT2020_CYCC (1 << 5)
+#define DRM_EDID_CLRMETRY_BT2020_YCC  (1 << 6)
+#define DRM_EDID_CLRMETRY_BT2020_RGB  (1 << 7)
+#define DRM_EDID_CLRMETRY_DCI_P3      (1 << 15)
+
 /* ELD Header Block */
 #define DRM_ELD_HEADER_BLOCK_SIZE	4

--
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