Re: [PATCH v2 13/15] drm/edid: add HF-EEODB support to EDID read and allocation

On Wed, Jun 08, 2022 at 10:50:43AM +0300, Jani Nikula wrote:

HDMI 2.1 section 10.3.6 defines an HDMI Forum EDID Extension Override Data Block, which may contain a different extension count than the base block claims. Add support for reading more EDID data if available. The extra blocks aren't parsed yet, though.

Hard-coding the EEODB parsing instead of using the iterators we have is a bit of a bummer, but we have to be able to do this on a partially allocated EDID while reading it.

v2:

• Check for CEA Data Block Collection size (Ville)
• Amend commit message and comment about hard-coded parsing

Signed-off-by: Jani Nikula jani.nikula@intel.com

Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com

---

drivers/gpu/drm/drm_edid.c | 89 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 86 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 77ec5b0e436d..5cac357e50b0 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1581,6 +1581,15 @@ static bool version_greater(const struct drm_edid *drm_edid, (edid->version == version && edid->revision > revision); }

+static int edid_hfeeodb_extension_block_count(const struct edid *edid);

+static int edid_hfeeodb_block_count(const struct edid *edid) +{

• int eeodb = edid_hfeeodb_extension_block_count(edid);
• return eeodb ? eeodb + 1 : 0;

+}

static int edid_extension_block_count(const struct edid *edid) { return edid->extensions; @@ -2026,6 +2035,11 @@ static struct edid *edid_filter_invalid_blocks(struct edid *edid, struct edid *new; int i, valid_blocks = 0;

• /*

• * Note: If the EDID uses HF-EEODB, but has invalid blocks, we'll revert
  

• * back to regular extension count here. We don't want to start
  

• * modifying the HF-EEODB extension too.
  

• */
  

  for (i = 0; i < edid_block_count(edid); i++) { const void *src_block = edid_block_data(edid, i);

@@ -2235,7 +2249,7 @@ static struct edid *_drm_do_get_edid(struct drm_connector *connector, size_t *size) { enum edid_block_status status;

• int i, invalid_blocks = 0;

• int i, num_blocks, invalid_blocks = 0; struct edid *edid, *new; size_t alloc_size = EDID_LENGTH;

@@ -2277,7 +2291,8 @@ static struct edid *_drm_do_get_edid(struct drm_connector *connector, goto fail; edid = new;

• for (i = 1; i < edid_block_count(edid); i++) {

• num_blocks = edid_block_count(edid);

• for (i = 1; i < num_blocks; i++) { void *block = (void *)edid_block_data(edid, i);

  status = edid_block_read(block, i, read_block, context);

@@ -2288,11 +2303,31 @@ static struct edid *_drm_do_get_edid(struct drm_connector *connector, if (status == EDID_BLOCK_READ_FAIL) goto fail; invalid_blocks++;

• } else if (i == 1) {
  

• 	/*
  

• 	 * If the first EDID extension is a CTA extension, and
  

• 	 * the first Data Block is HF-EEODB, override the
  

• 	 * extension block count.
  

• 	 *
  

• 	 * Note: HF-EEODB could specify a smaller extension
  

• 	 * count too, but we can't risk allocating a smaller
  

• 	 * amount.
  

• 	 */
  

• 	int eeodb = edid_hfeeodb_block_count(edid);
  

• 	if (eeodb > num_blocks) {
  

• 		num_blocks = eeodb;
  

• 		alloc_size = edid_size_by_blocks(num_blocks);
  

• 		new = krealloc(edid, alloc_size, GFP_KERNEL);
  

• 		if (!new)
  

• 			goto fail;
  

• 		edid = new;
  

• 	}
  

  } }

  if (invalid_blocks) {

• connector_bad_edid(connector, edid, edid_block_count(edid));
  

• connector_bad_edid(connector, edid, num_blocks);
  
  

  edid = edid_filter_invalid_blocks(edid, &alloc_size); }

@@ -3825,6 +3860,7 @@ static int add_detailed_modes(struct drm_connector *connector, #define CTA_EXT_DB_HDR_STATIC_METADATA 6 #define CTA_EXT_DB_420_VIDEO_DATA 14 #define CTA_EXT_DB_420_VIDEO_CAP_MAP 15 +#define CTA_EXT_DB_HF_EEODB 0x78 #define CTA_EXT_DB_HF_SCDB 0x79

#define EDID_BASIC_AUDIO (1 << 6) @@ -4884,6 +4920,12 @@ static bool cea_db_is_hdmi_forum_vsdb(const struct cea_db *db) cea_db_payload_len(db) >= 7; }

+static bool cea_db_is_hdmi_forum_eeodb(const void *db) +{

• return cea_db_is_extended_tag(db, CTA_EXT_DB_HF_EEODB) &&

• cea_db_payload_len(db) >= 2;
  

+}

static bool cea_db_is_microsoft_vsdb(const struct cea_db *db) { return cea_db_is_vendor(db, MICROSOFT_IEEE_OUI) && @@ -4918,6 +4960,47 @@ static bool cea_db_is_hdmi_hdr_metadata_block(const struct cea_db *db) cea_db_payload_len(db) >= 3; }

+/*

• • Get the HF-EEODB override extension block count from EDID.
• • The passed in EDID may be partially read, as long as it has at least two
• • blocks (base block and one extension block) if EDID extension count is > 0.
• • Note that this is *not* how you should parse CTA Data Blocks in general; this
• • is only to handle partially read EDIDs. Normally, use the CTA Data Block
• • iterators instead.
• • References:
• • • HDMI 2.1 section 10.3.6 HDMI Forum EDID Extension Override Data Block
• */

+static int edid_hfeeodb_extension_block_count(const struct edid *edid) +{

• const u8 *cta;
• /* No extensions according to base block, no HF-EEODB. */
• if (!edid_extension_block_count(edid))

• return 0;
  

• /* HF-EEODB is always in the first EDID extension block only */
• cta = edid_extension_block_data(edid, 0);
• if (edid_block_tag(cta) != CEA_EXT || cea_revision(cta) < 3)

• return 0;
  

• /* Need to have the data block collection, and at least 3 bytes. */
• if (cea_db_collection_size(cta) < 3)

• return 0;
  

• /*

• * Sinks that include the HF-EEODB in their E-EDID shall include one and
  

• * only one instance of the HF-EEODB in the E-EDID, occupying bytes 4
  

• * through 6 of Block 1 of the E-EDID.
  

• */
  

• if (!cea_db_is_hdmi_forum_eeodb(&cta[4]))

• return 0;
  

• return cta[4 + 2];

+}

static void drm_parse_y420cmdb_bitmap(struct drm_connector *connector, const u8 *db) { -- 2.30.2