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@xxxxxxxxx>
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> 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
--
Ville Syrjälä
Intel
