On Thu, 17 Mar 2022, Lee Shawn C <shawn.c.lee@xxxxxxxxx> 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@xxxxxxxxxxxxxxx>
> Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> Cc: intel-gfx <intel-gfx@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Lee Shawn C <shawn.c.lee@xxxxxxxxx>
> ---
> 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
