[v8 0/5] enhanced edid driver compatibility

[v8 0/5] enhanced edid driver compatibility

[Lee Shawn C]

Support to parse multiple CEA extension blocks and HF-EEODB to
extend drm edid driver's capability.

v4: add one more patch to support HF-SCDB
v5: HF-SCDB and HF-VSDBS carry the same SCDS data. Reuse
    drm_parse_hdmi_forum_vsdb() to parse this packet.
v6: save proper extension block index if CTA data information
    was found in DispalyID block.
v7: using different parameters to store CEA and DisplayID block index.
    configure DisplayID extansion block index before search available
    DisplayID block.
v8: revert patch [v7 2/5] change.
    And check cea pointer return from drm_find_cea_extension().
    If drvier got the same cea pointer then exit this routine.

Lee Shawn C (5):
  drm/edid: seek for available CEA block from specific EDID block index
  drm/edid: parse multiple CEA extension block
  drm/edid: read HF-EEODB ext block
  drm/edid: parse HF-EEODB CEA extension block
  drm/edid: check for HF-SCDB block

 drivers/gpu/drm/drm_connector.c |   8 +-
 drivers/gpu/drm/drm_displayid.c |   5 +-
 drivers/gpu/drm/drm_edid.c      | 174 ++++++++++++++++++++++++--------
 include/drm/drm_edid.h          |   4 +-
 4 files changed, 144 insertions(+), 47 deletions(-)

-- 
2.17.1

[v8 1/5] drm/edid: seek for available CEA block from specific EDID block index

[Lee Shawn C]

drm_find_cea_extension() always look for a top level CEA block. Pass
ext_index from caller then this function to search next available
CEA ext block from a specific EDID block pointer.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
---
 drivers/gpu/drm/drm_edid.c | 42 ++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 561f53831e29..1251226d9284 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3353,16 +3353,14 @@ const u8 *drm_find_edid_extension(const struct edid *edid,
 	return edid_ext;
 }
 
-static const u8 *drm_find_cea_extension(const struct edid *edid)
+static const u8 *drm_find_cea_extension(const struct edid *edid, int *ext_index)
 {
 	const struct displayid_block *block;
 	struct displayid_iter iter;
 	const u8 *cea;
-	int ext_index = 0;
 
-	/* Look for a top level CEA extension block */
-	/* FIXME: make callers iterate through multiple CEA ext blocks? */
-	cea = drm_find_edid_extension(edid, CEA_EXT, &ext_index);
+	/* Look for a CEA extension block from ext_index */
+	cea = drm_find_edid_extension(edid, CEA_EXT, ext_index);
 	if (cea)
 		return cea;
 
@@ -3643,10 +3641,10 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
 	struct drm_device *dev = connector->dev;
 	struct drm_display_mode *mode, *tmp;
 	LIST_HEAD(list);
-	int modes = 0;
+	int modes = 0, ext_index = 0;
 
 	/* Don't add CEA modes if the CEA extension block is missing */
-	if (!drm_find_cea_extension(edid))
+	if (!drm_find_cea_extension(edid, &ext_index))
 		return 0;
 
 	/*
@@ -4321,11 +4319,11 @@ static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
 static int
 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;
+	const u8 *cea, *db, *hdmi = NULL, *video = NULL;
 	u8 dbl, hdmi_len, video_len = 0;
-	int modes = 0;
+	int modes = 0, ext_index = 0;
 
+	cea = drm_find_cea_extension(edid, &ext_index);
 	if (cea && cea_revision(cea) >= 3) {
 		int i, start, end;
 
@@ -4562,7 +4560,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
 	uint8_t *eld = connector->eld;
 	const u8 *cea;
 	const u8 *db;
-	int total_sad_count = 0;
+	int total_sad_count = 0, ext_index = 0;
 	int mnl;
 	int dbl;
 
@@ -4571,7 +4569,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
 	if (!edid)
 		return;
 
-	cea = drm_find_cea_extension(edid);
+	cea = drm_find_cea_extension(edid, &ext_index);
 	if (!cea) {
 		DRM_DEBUG_KMS("ELD: no CEA Extension found\n");
 		return;
@@ -4655,11 +4653,11 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
  */
 int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads)
 {
-	int count = 0;
+	int count = 0, ext_index = 0;
 	int i, start, end, dbl;
 	const u8 *cea;
 
-	cea = drm_find_cea_extension(edid);
+	cea = drm_find_cea_extension(edid, &ext_index);
 	if (!cea) {
 		DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
 		return 0;
@@ -4717,11 +4715,11 @@ EXPORT_SYMBOL(drm_edid_to_sad);
  */
 int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
 {
-	int count = 0;
+	int count = 0, ext_index = 0;
 	int i, start, end, dbl;
 	const u8 *cea;
 
-	cea = drm_find_cea_extension(edid);
+	cea = drm_find_cea_extension(edid, &ext_index);
 	if (!cea) {
 		DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
 		return 0;
@@ -4814,9 +4812,9 @@ bool drm_detect_hdmi_monitor(struct edid *edid)
 {
 	const u8 *edid_ext;
 	int i;
-	int start_offset, end_offset;
+	int start_offset, end_offset, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid);
+	edid_ext = drm_find_cea_extension(edid, &ext_index);
 	if (!edid_ext)
 		return false;
 
@@ -4853,9 +4851,9 @@ bool drm_detect_monitor_audio(struct edid *edid)
 	const u8 *edid_ext;
 	int i, j;
 	bool has_audio = false;
-	int start_offset, end_offset;
+	int start_offset, end_offset, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid);
+	edid_ext = drm_find_cea_extension(edid, &ext_index);
 	if (!edid_ext)
 		goto end;
 
@@ -5177,9 +5175,9 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 {
 	struct drm_display_info *info = &connector->display_info;
 	const u8 *edid_ext;
-	int i, start, end;
+	int i, start, end, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid);
+	edid_ext = drm_find_cea_extension(edid, &ext_index);
 	if (!edid_ext)
 		return;
 
-- 
2.17.1

[v8 2/5] drm/edid: parse multiple CEA extension block

[Lee Shawn C]

Try to find and parse more CEA ext blocks if edid->extensions
is greater than one.

v2: split prvious patch to two. And do CEA block parsing
    in this one.
v3: simplify this patch based on previous change.
v4: refine patch v3.
v5: revert previous change.
    And check cea pointer return from drm_find_cea_extension().
    If drvier got the same cea pointer then exit this routine.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Drew Davenport <ddavenport@chromium.org>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
---
 drivers/gpu/drm/drm_edid.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 1251226d9284..ef65dd97d700 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4319,16 +4319,24 @@ static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
 static int
 add_cea_modes(struct drm_connector *connector, struct edid *edid)
 {
-	const u8 *cea, *db, *hdmi = NULL, *video = NULL;
-	u8 dbl, hdmi_len, video_len = 0;
 	int modes = 0, ext_index = 0;
+	const u8 *cur_cea = NULL;
 
-	cea = drm_find_cea_extension(edid, &ext_index);
-	if (cea && cea_revision(cea) >= 3) {
+	for (;;) {
+		const u8 *cea, *db, *hdmi = NULL, *video = NULL;
+		u8 dbl, hdmi_len = 0, video_len = 0;
 		int i, start, end;
 
+		cea = drm_find_cea_extension(edid, &ext_index);
+		if (!cea || cea == cur_cea)
+			break;
+		cur_cea = cea;
+
+		if (cea_revision(cea) < 3)
+			continue;
+
 		if (cea_db_offsets(cea, &start, &end))
-			return 0;
+			continue;
 
 		for_each_cea_db(cea, i, start, end) {
 			db = &cea[i];
@@ -4350,15 +4358,15 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
 							  dbl - 1);
 			}
 		}
-	}
 
-	/*
-	 * We parse the HDMI VSDB after having added the cea modes as we will
-	 * be patching their flags when the sink supports stereo 3D.
-	 */
-	if (hdmi)
-		modes += do_hdmi_vsdb_modes(connector, hdmi, hdmi_len, video,
-					    video_len);
+		/*
+		 * We parse the HDMI VSDB after having added the cea modes as we will
+		 * be patching their flags when the sink supports stereo 3D.
+		 */
+		if (hdmi)
+			modes += do_hdmi_vsdb_modes(connector, hdmi, hdmi_len, video,
+						    video_len);
+	}
 
 	return modes;
 }
-- 
2.17.1

[v8 3/5] drm/edid: read HF-EEODB ext block

[Lee Shawn C]

According to HDMI 2.1 spec.

"The HDMI Forum EDID Extension Override Data Block (HF-EEODB)
is utilized by Sink Devices to provide an alternate method to
indicate an EDID Extension Block count larger than 1, while
avoiding the need to present a VESA Block Map in the first
E-EDID Extension Block."

It is a mandatory for HDMI 2.1 protocol compliance as well.
This patch help to know how many HF_EEODB blocks report by sink
and read allo HF_EEODB blocks back.

v2: support to find CEA block, check EEODB block format, and return
    available block number in drm_edid_read_hf_eeodb_blk_count().

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
---
 drivers/gpu/drm/drm_connector.c |  8 +++-
 drivers/gpu/drm/drm_edid.c      | 71 +++++++++++++++++++++++++++++++--
 include/drm/drm_edid.h          |  2 +-
 3 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index a50c82bc2b2f..16011023c12e 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2129,7 +2129,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 				       const struct edid *edid)
 {
 	struct drm_device *dev = connector->dev;
-	size_t size = 0;
+	size_t size = 0, hf_eeodb_blk_count;
 	int ret;
 	const struct edid *old_edid;
 
@@ -2137,8 +2137,12 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	if (connector->override_edid)
 		return 0;
 
-	if (edid)
+	if (edid) {
 		size = EDID_LENGTH * (1 + edid->extensions);
+		hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count(edid);
+		if (hf_eeodb_blk_count)
+			size = EDID_LENGTH * (1 + hf_eeodb_blk_count);
+	}
 
 	/* Set the display info, using edid if available, otherwise
 	 * resetting the values to defaults. This duplicates the work
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index ef65dd97d700..890038758660 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1992,6 +1992,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 {
 	int i, j = 0, valid_extensions = 0;
 	u8 *edid, *new;
+	size_t hf_eeodb_blk_count;
 	struct edid *override;
 
 	override = drm_get_override_edid(connector);
@@ -2051,7 +2052,35 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 		}
 
 		kfree(edid);
+		return (struct edid *)new;
+	}
+
+	hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count((struct edid *)edid);
+	if (hf_eeodb_blk_count >= 2) {
+		new = krealloc(edid, (hf_eeodb_blk_count + 1) * EDID_LENGTH, GFP_KERNEL);
+		if (!new)
+			goto out;
 		edid = new;
+
+		valid_extensions = hf_eeodb_blk_count - 1;
+		for (j = 2; j <= hf_eeodb_blk_count; j++) {
+			u8 *block = edid + j * EDID_LENGTH;
+
+			for (i = 0; i < 4; i++) {
+				if (get_edid_block(data, block, j, EDID_LENGTH))
+					goto out;
+				if (drm_edid_block_valid(block, j, false, NULL))
+					break;
+			}
+
+			if (i == 4)
+				valid_extensions--;
+		}
+
+		if (valid_extensions != hf_eeodb_blk_count - 1) {
+			DRM_ERROR("Not able to retrieve proper EDID contain HF-EEODB data.\n");
+			goto out;
+		}
 	}
 
 	return (struct edid *)edid;
@@ -3315,15 +3344,17 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
 #define VIDEO_BLOCK     0x02
 #define VENDOR_BLOCK    0x03
 #define SPEAKER_BLOCK	0x04
-#define HDR_STATIC_METADATA_BLOCK	0x6
-#define USE_EXTENDED_TAG 0x07
-#define EXT_VIDEO_CAPABILITY_BLOCK 0x00
+#define EXT_VIDEO_CAPABILITY_BLOCK	0x00
+#define HDR_STATIC_METADATA_BLOCK	0x06
+#define USE_EXTENDED_TAG		0x07
 #define EXT_VIDEO_DATA_BLOCK_420	0x0E
-#define EXT_VIDEO_CAP_BLOCK_Y420CMDB 0x0F
+#define EXT_VIDEO_CAP_BLOCK_Y420CMDB	0x0F
+#define EXT_VIDEO_HF_EEODB_DATA_BLOCK	0x78
 #define EDID_BASIC_AUDIO	(1 << 6)
 #define EDID_CEA_YCRCB444	(1 << 5)
 #define EDID_CEA_YCRCB422	(1 << 4)
 #define EDID_CEA_VCDB_QS	(1 << 6)
+#define HF_EEODB_LENGTH		2
 
 /*
  * Search EDID for CEA extension block.
@@ -4273,9 +4304,41 @@ static bool cea_db_is_y420vdb(const u8 *db)
 	return true;
 }
 
+static bool cea_db_is_hdmi_forum_eeodb(const u8 *db)
+{
+	if (cea_db_tag(db) != USE_EXTENDED_TAG)
+		return false;
+
+	if (cea_db_payload_len(db) != HF_EEODB_LENGTH)
+		return false;
+
+	if (cea_db_extended_tag(db) != EXT_VIDEO_HF_EEODB_DATA_BLOCK)
+		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)
 
+size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid)
+{
+	const u8 *cea;
+	int i, start, end, ext_index = 0;
+
+	if (edid->extensions) {
+		cea = drm_find_cea_extension(edid, &ext_index);
+
+		if (cea && !cea_db_offsets(cea, &start, &end))
+			for_each_cea_db(cea, i, start, end)
+				if (cea_db_is_hdmi_forum_eeodb(&cea[i]))
+					return cea[i + 2];
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(drm_edid_read_hf_eeodb_blk_count);
+
 static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
 				      const u8 *db)
 {
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 144c495b99c4..5549da7bd7be 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -592,6 +592,6 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
 			      u8 video_code);
 const u8 *drm_find_edid_extension(const struct edid *edid,
 				  int ext_id, int *ext_index);
-
+size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid);
 
 #endif /* __DRM_EDID_H__ */
-- 
2.17.1

[v8 4/5] drm/edid: parse HF-EEODB CEA extension block

[Lee Shawn C]

While adding CEA modes, try to get available EEODB block
number. Then based on it to parse numbers of ext blocks,
retrieve CEA information and add more CEA modes.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
---
 drivers/gpu/drm/drm_displayid.c |  5 ++++-
 drivers/gpu/drm/drm_edid.c      | 35 +++++++++++++++++++--------------
 include/drm/drm_edid.h          |  2 +-
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/drm_displayid.c b/drivers/gpu/drm/drm_displayid.c
index 32da557b960f..dc649a9efaa2 100644
--- a/drivers/gpu/drm/drm_displayid.c
+++ b/drivers/gpu/drm/drm_displayid.c
@@ -37,7 +37,10 @@ static const u8 *drm_find_displayid_extension(const struct edid *edid,
 					      int *length, int *idx,
 					      int *ext_index)
 {
-	const u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT, ext_index);
+	const u8 *displayid = drm_find_edid_extension(edid,
+						      DISPLAYID_EXT,
+						      ext_index,
+						      edid->extensions);
 	const struct displayid_header *base;
 	int ret;
 
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 890038758660..40c192587f0a 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3360,23 +3360,23 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
  * Search EDID for CEA extension block.
  */
 const u8 *drm_find_edid_extension(const struct edid *edid,
-				  int ext_id, int *ext_index)
+				  int ext_id, int *ext_index, int ext_blk_num)
 {
 	const u8 *edid_ext = NULL;
 	int i;
 
 	/* No EDID or EDID extensions */
-	if (edid == NULL || edid->extensions == 0)
+	if (edid == NULL || edid->extensions == 0 || *ext_index >= ext_blk_num)
 		return NULL;
 
 	/* Find CEA extension */
-	for (i = *ext_index; i < edid->extensions; i++) {
+	for (i = *ext_index; i < ext_blk_num; i++) {
 		edid_ext = (const u8 *)edid + EDID_LENGTH * (i + 1);
 		if (edid_ext[0] == ext_id)
 			break;
 	}
 
-	if (i >= edid->extensions)
+	if (i >= ext_blk_num)
 		return NULL;
 
 	*ext_index = i + 1;
@@ -3384,14 +3384,15 @@ const u8 *drm_find_edid_extension(const struct edid *edid,
 	return edid_ext;
 }
 
-static const u8 *drm_find_cea_extension(const struct edid *edid, int *ext_index)
+static const u8 *drm_find_cea_extension(const struct edid *edid,
+					int *ext_index, int ext_blk_num)
 {
 	const struct displayid_block *block;
 	struct displayid_iter iter;
 	const u8 *cea;
 
 	/* Look for a CEA extension block from ext_index */
-	cea = drm_find_edid_extension(edid, CEA_EXT, ext_index);
+	cea = drm_find_edid_extension(edid, CEA_EXT, ext_index, ext_blk_num);
 	if (cea)
 		return cea;
 
@@ -3675,7 +3676,7 @@ add_alternate_cea_modes(struct drm_connector *connector, struct edid *edid)
 	int modes = 0, ext_index = 0;
 
 	/* Don't add CEA modes if the CEA extension block is missing */
-	if (!drm_find_cea_extension(edid, &ext_index))
+	if (!drm_find_cea_extension(edid, &ext_index, edid->extensions))
 		return 0;
 
 	/*
@@ -4327,7 +4328,7 @@ size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid)
 	int i, start, end, ext_index = 0;
 
 	if (edid->extensions) {
-		cea = drm_find_cea_extension(edid, &ext_index);
+		cea = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 
 		if (cea && !cea_db_offsets(cea, &start, &end))
 			for_each_cea_db(cea, i, start, end)
@@ -4384,13 +4385,17 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
 {
 	int modes = 0, ext_index = 0;
 	const u8 *cur_cea = NULL;
+	int ext_blk_num = drm_edid_read_hf_eeodb_blk_count(edid);
+
+	if (!ext_blk_num)
+		ext_blk_num = edid->extensions;
 
 	for (;;) {
 		const u8 *cea, *db, *hdmi = NULL, *video = NULL;
 		u8 dbl, hdmi_len = 0, video_len = 0;
 		int i, start, end;
 
-		cea = drm_find_cea_extension(edid, &ext_index);
+		cea = drm_find_cea_extension(edid, &ext_index, ext_blk_num);
 		if (!cea || cea == cur_cea)
 			break;
 		cur_cea = cea;
@@ -4640,7 +4645,7 @@ static void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
 	if (!edid)
 		return;
 
-	cea = drm_find_cea_extension(edid, &ext_index);
+	cea = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!cea) {
 		DRM_DEBUG_KMS("ELD: no CEA Extension found\n");
 		return;
@@ -4728,7 +4733,7 @@ int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads)
 	int i, start, end, dbl;
 	const u8 *cea;
 
-	cea = drm_find_cea_extension(edid, &ext_index);
+	cea = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!cea) {
 		DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
 		return 0;
@@ -4790,7 +4795,7 @@ int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
 	int i, start, end, dbl;
 	const u8 *cea;
 
-	cea = drm_find_cea_extension(edid, &ext_index);
+	cea = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!cea) {
 		DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
 		return 0;
@@ -4885,7 +4890,7 @@ bool drm_detect_hdmi_monitor(struct edid *edid)
 	int i;
 	int start_offset, end_offset, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid, &ext_index);
+	edid_ext = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!edid_ext)
 		return false;
 
@@ -4924,7 +4929,7 @@ bool drm_detect_monitor_audio(struct edid *edid)
 	bool has_audio = false;
 	int start_offset, end_offset, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid, &ext_index);
+	edid_ext = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!edid_ext)
 		goto end;
 
@@ -5248,7 +5253,7 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 	const u8 *edid_ext;
 	int i, start, end, ext_index = 0;
 
-	edid_ext = drm_find_cea_extension(edid, &ext_index);
+	edid_ext = drm_find_cea_extension(edid, &ext_index, edid->extensions);
 	if (!edid_ext)
 		return;
 
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 5549da7bd7be..5555b27e92f9 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -591,7 +591,7 @@ struct drm_display_mode *
 drm_display_mode_from_cea_vic(struct drm_device *dev,
 			      u8 video_code);
 const u8 *drm_find_edid_extension(const struct edid *edid,
-				  int ext_id, int *ext_index);
+				  int ext_id, int *ext_index, int ext_blk_num);
 size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid);
 
 #endif /* __DRM_EDID_H__ */
-- 
2.17.1

[v8 5/5] drm/edid: check for HF-SCDB block

[Lee Shawn C]

Find HF-SCDB information in CEA extensions block. And retrieve
Max_TMDS_Character_Rate that support by sink device.

v2: HF-SCDB and HF-VSDBS carry the same SCDS data. Reuse
    drm_parse_hdmi_forum_vsdb() to parse this packet.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
---
 drivers/gpu/drm/drm_edid.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 40c192587f0a..64d13ba0f701 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3350,6 +3350,7 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
 #define EXT_VIDEO_DATA_BLOCK_420	0x0E
 #define EXT_VIDEO_CAP_BLOCK_Y420CMDB	0x0F
 #define EXT_VIDEO_HF_EEODB_DATA_BLOCK	0x78
+#define EXT_VIDEO_HF_SCDB_DATA_BLOCK	0x79
 #define EDID_BASIC_AUDIO	(1 << 6)
 #define EDID_CEA_YCRCB444	(1 << 5)
 #define EDID_CEA_YCRCB422	(1 << 4)
@@ -4277,6 +4278,20 @@ static bool cea_db_is_vcdb(const u8 *db)
 	return true;
 }
 
+static bool cea_db_is_hdmi_forum_scdb(const u8 *db)
+{
+	if (cea_db_tag(db) != USE_EXTENDED_TAG)
+		return false;
+
+	if (cea_db_payload_len(db) < 7)
+		return false;
+
+	if (cea_db_extended_tag(db) != EXT_VIDEO_HF_SCDB_DATA_BLOCK)
+		return false;
+
+	return true;
+}
+
 static bool cea_db_is_y420cmdb(const u8 *db)
 {
 	if (cea_db_tag(db) != USE_EXTENDED_TAG)
@@ -5274,7 +5289,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 
 		if (cea_db_is_hdmi_vsdb(db))
 			drm_parse_hdmi_vsdb_video(connector, db);
-		if (cea_db_is_hdmi_forum_vsdb(db))
+		if (cea_db_is_hdmi_forum_vsdb(db) ||
+		    cea_db_is_hdmi_forum_scdb(db))
 			drm_parse_hdmi_forum_vsdb(connector, db);
 		if (cea_db_is_microsoft_vsdb(db))
 			drm_parse_microsoft_vsdb(connector, db);
-- 
2.17.1

Re: [v8 3/5] drm/edid: read HF-EEODB ext block

[Jani Nikula]

On Thu, 17 Mar 2022, Lee Shawn C <shawn.c.lee@intel.com> wrote:
> According to HDMI 2.1 spec.
>
> "The HDMI Forum EDID Extension Override Data Block (HF-EEODB)
> is utilized by Sink Devices to provide an alternate method to
> indicate an EDID Extension Block count larger than 1, while
> avoiding the need to present a VESA Block Map in the first
> E-EDID Extension Block."
>
> It is a mandatory for HDMI 2.1 protocol compliance as well.
> This patch help to know how many HF_EEODB blocks report by sink
> and read allo HF_EEODB blocks back.

It still just boggles my mind that they've implemented something like
this. They cite avoiding the EDID Block Map as the rationale... but it's
been optional since E-EDID structure v1.4, published in 2006. 15+ years
ago.

Can anyone tell me a sane reason for this? What does it provide that
E-EDID 1.4 does not? Do they want to use E-EDID v1.3 with this? Why?

BR,
Jani.


>
> v2: support to find CEA block, check EEODB block format, and return
>     available block number in drm_edid_read_hf_eeodb_blk_count().
>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
> ---
>  drivers/gpu/drm/drm_connector.c |  8 +++-
>  drivers/gpu/drm/drm_edid.c      | 71 +++++++++++++++++++++++++++++++--
>  include/drm/drm_edid.h          |  2 +-
>  3 files changed, 74 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index a50c82bc2b2f..16011023c12e 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -2129,7 +2129,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
>  				       const struct edid *edid)
>  {
>  	struct drm_device *dev = connector->dev;
> -	size_t size = 0;
> +	size_t size = 0, hf_eeodb_blk_count;
>  	int ret;
>  	const struct edid *old_edid;
>  
> @@ -2137,8 +2137,12 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
>  	if (connector->override_edid)
>  		return 0;
>  
> -	if (edid)
> +	if (edid) {
>  		size = EDID_LENGTH * (1 + edid->extensions);
> +		hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count(edid);
> +		if (hf_eeodb_blk_count)
> +			size = EDID_LENGTH * (1 + hf_eeodb_blk_count);
> +	}
>  
>  	/* Set the display info, using edid if available, otherwise
>  	 * resetting the values to defaults. This duplicates the work
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index ef65dd97d700..890038758660 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1992,6 +1992,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>  {
>  	int i, j = 0, valid_extensions = 0;
>  	u8 *edid, *new;
> +	size_t hf_eeodb_blk_count;
>  	struct edid *override;
>  
>  	override = drm_get_override_edid(connector);
> @@ -2051,7 +2052,35 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>  		}
>  
>  		kfree(edid);
> +		return (struct edid *)new;
> +	}
> +
> +	hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count((struct edid *)edid);
> +	if (hf_eeodb_blk_count >= 2) {
> +		new = krealloc(edid, (hf_eeodb_blk_count + 1) * EDID_LENGTH, GFP_KERNEL);
> +		if (!new)
> +			goto out;
>  		edid = new;
> +
> +		valid_extensions = hf_eeodb_blk_count - 1;
> +		for (j = 2; j <= hf_eeodb_blk_count; j++) {
> +			u8 *block = edid + j * EDID_LENGTH;
> +
> +			for (i = 0; i < 4; i++) {
> +				if (get_edid_block(data, block, j, EDID_LENGTH))
> +					goto out;
> +				if (drm_edid_block_valid(block, j, false, NULL))
> +					break;
> +			}
> +
> +			if (i == 4)
> +				valid_extensions--;
> +		}
> +
> +		if (valid_extensions != hf_eeodb_blk_count - 1) {
> +			DRM_ERROR("Not able to retrieve proper EDID contain HF-EEODB data.\n");
> +			goto out;
> +		}
>  	}
>  
>  	return (struct edid *)edid;
> @@ -3315,15 +3344,17 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
>  #define VIDEO_BLOCK     0x02
>  #define VENDOR_BLOCK    0x03
>  #define SPEAKER_BLOCK	0x04
> -#define HDR_STATIC_METADATA_BLOCK	0x6
> -#define USE_EXTENDED_TAG 0x07
> -#define EXT_VIDEO_CAPABILITY_BLOCK 0x00
> +#define EXT_VIDEO_CAPABILITY_BLOCK	0x00
> +#define HDR_STATIC_METADATA_BLOCK	0x06
> +#define USE_EXTENDED_TAG		0x07
>  #define EXT_VIDEO_DATA_BLOCK_420	0x0E
> -#define EXT_VIDEO_CAP_BLOCK_Y420CMDB 0x0F
> +#define EXT_VIDEO_CAP_BLOCK_Y420CMDB	0x0F
> +#define EXT_VIDEO_HF_EEODB_DATA_BLOCK	0x78
>  #define EDID_BASIC_AUDIO	(1 << 6)
>  #define EDID_CEA_YCRCB444	(1 << 5)
>  #define EDID_CEA_YCRCB422	(1 << 4)
>  #define EDID_CEA_VCDB_QS	(1 << 6)
> +#define HF_EEODB_LENGTH		2
>  
>  /*
>   * Search EDID for CEA extension block.
> @@ -4273,9 +4304,41 @@ static bool cea_db_is_y420vdb(const u8 *db)
>  	return true;
>  }
>  
> +static bool cea_db_is_hdmi_forum_eeodb(const u8 *db)
> +{
> +	if (cea_db_tag(db) != USE_EXTENDED_TAG)
> +		return false;
> +
> +	if (cea_db_payload_len(db) != HF_EEODB_LENGTH)
> +		return false;
> +
> +	if (cea_db_extended_tag(db) != EXT_VIDEO_HF_EEODB_DATA_BLOCK)
> +		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)
>  
> +size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid)
> +{
> +	const u8 *cea;
> +	int i, start, end, ext_index = 0;
> +
> +	if (edid->extensions) {
> +		cea = drm_find_cea_extension(edid, &ext_index);
> +
> +		if (cea && !cea_db_offsets(cea, &start, &end))
> +			for_each_cea_db(cea, i, start, end)
> +				if (cea_db_is_hdmi_forum_eeodb(&cea[i]))
> +					return cea[i + 2];
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(drm_edid_read_hf_eeodb_blk_count);
> +
>  static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
>  				      const u8 *db)
>  {
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 144c495b99c4..5549da7bd7be 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -592,6 +592,6 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
>  			      u8 video_code);
>  const u8 *drm_find_edid_extension(const struct edid *edid,
>  				  int ext_id, int *ext_index);
> -
> +size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid);
>  
>  #endif /* __DRM_EDID_H__ */

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [v8 3/5] drm/edid: read HF-EEODB ext block

[Jani Nikula]

On Wed, 23 Mar 2022, Jani Nikula <jani.nikula@intel.com> wrote:
> On Thu, 17 Mar 2022, Lee Shawn C <shawn.c.lee@intel.com> wrote:
>> According to HDMI 2.1 spec.
>>
>> "The HDMI Forum EDID Extension Override Data Block (HF-EEODB)
>> is utilized by Sink Devices to provide an alternate method to
>> indicate an EDID Extension Block count larger than 1, while
>> avoiding the need to present a VESA Block Map in the first
>> E-EDID Extension Block."
>>
>> It is a mandatory for HDMI 2.1 protocol compliance as well.
>> This patch help to know how many HF_EEODB blocks report by sink
>> and read allo HF_EEODB blocks back.
>
> It still just boggles my mind that they've implemented something like
> this. They cite avoiding the EDID Block Map as the rationale... but it's
> been optional since E-EDID structure v1.4, published in 2006. 15+ years
> ago.
>
> Can anyone tell me a sane reason for this? What does it provide that
> E-EDID 1.4 does not? Do they want to use E-EDID v1.3 with this? Why?

Oh, and the main problem with the whole thing, and this implementation?

If you have a struct edid *, there's no way way to tell if whoever
allocated the memory or copied the block was actually HF-EEODB aware.

Basically we'd have to audit every single piece of EDID handling code
across all drivers to see if they handle HF-EEODB properly. If we don't,
it's a question of time a struct edid * with HF-EEODB but no memory
allocated for the extensions gets passed to a function that understands
it, and overflows the buffer.

Simon and Daniel also tell me on IRC we can't just modify the base block
extension count to match HF-EEODB to dodge the problem, because the EDID
gets exposed to userspace.


BR,
Jani.



>
> BR,
> Jani.
>
>
>>
>> v2: support to find CEA block, check EEODB block format, and return
>>     available block number in drm_edid_read_hf_eeodb_blk_count().
>>
>> Cc: Jani Nikula <jani.nikula@linux.intel.com>
>> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
>> Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>> Cc: intel-gfx <intel-gfx@lists.freedesktop.org>
>> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
>> ---
>>  drivers/gpu/drm/drm_connector.c |  8 +++-
>>  drivers/gpu/drm/drm_edid.c      | 71 +++++++++++++++++++++++++++++++--
>>  include/drm/drm_edid.h          |  2 +-
>>  3 files changed, 74 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
>> index a50c82bc2b2f..16011023c12e 100644
>> --- a/drivers/gpu/drm/drm_connector.c
>> +++ b/drivers/gpu/drm/drm_connector.c
>> @@ -2129,7 +2129,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
>>  				       const struct edid *edid)
>>  {
>>  	struct drm_device *dev = connector->dev;
>> -	size_t size = 0;
>> +	size_t size = 0, hf_eeodb_blk_count;
>>  	int ret;
>>  	const struct edid *old_edid;
>>  
>> @@ -2137,8 +2137,12 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
>>  	if (connector->override_edid)
>>  		return 0;
>>  
>> -	if (edid)
>> +	if (edid) {
>>  		size = EDID_LENGTH * (1 + edid->extensions);
>> +		hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count(edid);
>> +		if (hf_eeodb_blk_count)
>> +			size = EDID_LENGTH * (1 + hf_eeodb_blk_count);
>> +	}
>>  
>>  	/* Set the display info, using edid if available, otherwise
>>  	 * resetting the values to defaults. This duplicates the work
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index ef65dd97d700..890038758660 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -1992,6 +1992,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>>  {
>>  	int i, j = 0, valid_extensions = 0;
>>  	u8 *edid, *new;
>> +	size_t hf_eeodb_blk_count;
>>  	struct edid *override;
>>  
>>  	override = drm_get_override_edid(connector);
>> @@ -2051,7 +2052,35 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
>>  		}
>>  
>>  		kfree(edid);
>> +		return (struct edid *)new;
>> +	}
>> +
>> +	hf_eeodb_blk_count = drm_edid_read_hf_eeodb_blk_count((struct edid *)edid);
>> +	if (hf_eeodb_blk_count >= 2) {
>> +		new = krealloc(edid, (hf_eeodb_blk_count + 1) * EDID_LENGTH, GFP_KERNEL);
>> +		if (!new)
>> +			goto out;
>>  		edid = new;
>> +
>> +		valid_extensions = hf_eeodb_blk_count - 1;
>> +		for (j = 2; j <= hf_eeodb_blk_count; j++) {
>> +			u8 *block = edid + j * EDID_LENGTH;
>> +
>> +			for (i = 0; i < 4; i++) {
>> +				if (get_edid_block(data, block, j, EDID_LENGTH))
>> +					goto out;
>> +				if (drm_edid_block_valid(block, j, false, NULL))
>> +					break;
>> +			}
>> +
>> +			if (i == 4)
>> +				valid_extensions--;
>> +		}
>> +
>> +		if (valid_extensions != hf_eeodb_blk_count - 1) {
>> +			DRM_ERROR("Not able to retrieve proper EDID contain HF-EEODB data.\n");
>> +			goto out;
>> +		}
>>  	}
>>  
>>  	return (struct edid *)edid;
>> @@ -3315,15 +3344,17 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
>>  #define VIDEO_BLOCK     0x02
>>  #define VENDOR_BLOCK    0x03
>>  #define SPEAKER_BLOCK	0x04
>> -#define HDR_STATIC_METADATA_BLOCK	0x6
>> -#define USE_EXTENDED_TAG 0x07
>> -#define EXT_VIDEO_CAPABILITY_BLOCK 0x00
>> +#define EXT_VIDEO_CAPABILITY_BLOCK	0x00
>> +#define HDR_STATIC_METADATA_BLOCK	0x06
>> +#define USE_EXTENDED_TAG		0x07
>>  #define EXT_VIDEO_DATA_BLOCK_420	0x0E
>> -#define EXT_VIDEO_CAP_BLOCK_Y420CMDB 0x0F
>> +#define EXT_VIDEO_CAP_BLOCK_Y420CMDB	0x0F
>> +#define EXT_VIDEO_HF_EEODB_DATA_BLOCK	0x78
>>  #define EDID_BASIC_AUDIO	(1 << 6)
>>  #define EDID_CEA_YCRCB444	(1 << 5)
>>  #define EDID_CEA_YCRCB422	(1 << 4)
>>  #define EDID_CEA_VCDB_QS	(1 << 6)
>> +#define HF_EEODB_LENGTH		2
>>  
>>  /*
>>   * Search EDID for CEA extension block.
>> @@ -4273,9 +4304,41 @@ static bool cea_db_is_y420vdb(const u8 *db)
>>  	return true;
>>  }
>>  
>> +static bool cea_db_is_hdmi_forum_eeodb(const u8 *db)
>> +{
>> +	if (cea_db_tag(db) != USE_EXTENDED_TAG)
>> +		return false;
>> +
>> +	if (cea_db_payload_len(db) != HF_EEODB_LENGTH)
>> +		return false;
>> +
>> +	if (cea_db_extended_tag(db) != EXT_VIDEO_HF_EEODB_DATA_BLOCK)
>> +		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)
>>  
>> +size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid)
>> +{
>> +	const u8 *cea;
>> +	int i, start, end, ext_index = 0;
>> +
>> +	if (edid->extensions) {
>> +		cea = drm_find_cea_extension(edid, &ext_index);
>> +
>> +		if (cea && !cea_db_offsets(cea, &start, &end))
>> +			for_each_cea_db(cea, i, start, end)
>> +				if (cea_db_is_hdmi_forum_eeodb(&cea[i]))
>> +					return cea[i + 2];
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(drm_edid_read_hf_eeodb_blk_count);
>> +
>>  static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector,
>>  				      const u8 *db)
>>  {
>> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
>> index 144c495b99c4..5549da7bd7be 100644
>> --- a/include/drm/drm_edid.h
>> +++ b/include/drm/drm_edid.h
>> @@ -592,6 +592,6 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
>>  			      u8 video_code);
>>  const u8 *drm_find_edid_extension(const struct edid *edid,
>>  				  int ext_id, int *ext_index);
>> -
>> +size_t drm_edid_read_hf_eeodb_blk_count(const struct edid *edid);
>>  
>>  #endif /* __DRM_EDID_H__ */

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [v8 3/5] drm/edid: read HF-EEODB ext block

[Simon Ser]

On Wednesday, March 23rd, 2022 at 13:02, Jani Nikula <jani.nikula@intel.com> wrote:

> Simon and Daniel also tell me on IRC we can't just modify the base block
> extension count to match HF-EEODB to dodge the problem, because the EDID
> gets exposed to userspace.

I'm not familiar how the EDID blob gets exposed to user-space. If the
EDID data gets copied when creating the blob, and the blob is created
before the kernel mutates the EDID to accomodate for HF-EEODB, then
this proposal might still be workable.

Re: [v8 3/5] drm/edid: read HF-EEODB ext block

[Jani Nikula]

On Wed, 23 Mar 2022, Simon Ser <contact@emersion.fr> wrote:
> On Wednesday, March 23rd, 2022 at 13:02, Jani Nikula <jani.nikula@intel.com> wrote:
>
>> Simon and Daniel also tell me on IRC we can't just modify the base block
>> extension count to match HF-EEODB to dodge the problem, because the EDID
>> gets exposed to userspace.
>
> I'm not familiar how the EDID blob gets exposed to user-space. If the
> EDID data gets copied when creating the blob, and the blob is created
> before the kernel mutates the EDID to accomodate for HF-EEODB, then
> this proposal might still be workable.

You'd still end up with tracking separate copies of the EDID, which is
not necessarily easier. There are almost 70 calls to update the
connector EDID property that gets exposed to userspace, and the call
sites would need to know which copy to pass.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [v8 3/5] drm/edid: read HF-EEODB ext block

[Ville Syrjälä]

On Wed, Mar 23, 2022 at 12:11:50PM +0200, Jani Nikula wrote:
> On Thu, 17 Mar 2022, Lee Shawn C <shawn.c.lee@intel.com> wrote:
> > According to HDMI 2.1 spec.
> >
> > "The HDMI Forum EDID Extension Override Data Block (HF-EEODB)
> > is utilized by Sink Devices to provide an alternate method to
> > indicate an EDID Extension Block count larger than 1, while
> > avoiding the need to present a VESA Block Map in the first
> > E-EDID Extension Block."
> >
> > It is a mandatory for HDMI 2.1 protocol compliance as well.
> > This patch help to know how many HF_EEODB blocks report by sink
> > and read allo HF_EEODB blocks back.
> 
> It still just boggles my mind that they've implemented something like
> this. They cite avoiding the EDID Block Map as the rationale... but it's
> been optional since E-EDID structure v1.4, published in 2006. 15+ years
> ago.
> 
> Can anyone tell me a sane reason for this? What does it provide that
> E-EDID 1.4 does not? Do they want to use E-EDID v1.3 with this? Why?

Looks to be pretty much the same approach as the DPCD extended
receiver cap mess we already have to deal with.

So I presume this is a hack to avoid breaking some garbage source
devices that explode when they see too many extension blocks,
or something along those lines.

-- 
Ville Syrjälä
Intel