On Tuesday, March 15, 2022 7:03 PM, Nikula, Jani <jani.nikula@xxxxxxxxx> wrote:
>On Sun, 13 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.
>>
>> 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: Drew Davenport <ddavenport@xxxxxxxxxxxx>
>> 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 | 1 +
>> 3 files changed, 74 insertions(+), 6 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);
>
>This approach does not scale. If the number of extensions and thus the total EDID size depend on HF-EEODB, this *must* be abstracted.
>
>Consider, for example, drm_edid_duplicate(), which only looks at
>edid->extensions. A subsequent HF-EEODB aware access on an EDID
>duplicated using drm_edid_duplicate() will access beyond the allocated buffer.
>
>Yes, it's a lot of work to introduce drm_edid_size() and
>drm_edid_extension_count() or similar, and use them everywhere, but this is what we must do. It's a lot more work to try to take HF-EEODB into account everywhere. The latter is going to be riddled with bugs with everyone doing it a little different.
>
As you mentioned, we should have new functions to provide proper EDID byte size or extension counter.
And reuse them to handle/retrieve EDID more accurately in drm driver. Thanks for your comment!
>> + }
>>
>> /* 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
>> 9fa84881fbba..5ae4e83fa5e3 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.
>> @@ -4274,9 +4305,41 @@ 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, cea_ext_index = 0, displayid_ext_index = 0;
>> +
>> + if (edid->extensions) {
>> + cea = drm_find_cea_extension(edid, &cea_ext_index,
>> +&displayid_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);
>
>This should be static and not exported.
>
>BR,
>Jani.
>
>> +
>> 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..585f0ed932d4 100644
>> --- a/include/drm/drm_edid.h
>> +++ b/include/drm/drm_edid.h
>> @@ -593,5 +593,6 @@ drm_display_mode_from_cea_vic(struct drm_device
>> *dev, 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
