Re: [PATCH v3 1/4] drm/edid: Parse AMD VSDB for FreeSync refresh range

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The maximum payload length check in `cea_db_is_amd_vsdb()` rejects payloads larger than 21 bytes, silently breaking the intended forward compatibility for future VSDB versions.
--

--- Patch [1]: [PATCH v3 1/4] drm/edid: Parse AMD VSDB for FreeSync refresh range ---
commit 26fe9de2b3686b271fb4f7932172730167732cdb
Author: Alex Huang <Alex.Huang2@amd.com>

drm/edid: Parse AMD VSDB for FreeSync refresh range

This commit restructures the AMD VSDB parser to support FreeSync refresh
range fields from version 1 and 2 blocks. It also updates the parser to
handle versions > 3 as if they were version 3 for forward compatibility.

> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index df3c25bac761d..a12b5e6905fb7 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c

[ ... ]

> @@ -5231,7 +5259,7 @@ static bool cea_db_is_microsoft_vsdb(const struct cea_db *db)
>  static bool cea_db_is_amd_vsdb(const struct cea_db *db)
>  {
>  	return cea_db_is_vendor(db, AMD_IEEE_OUI) &&
> -		cea_db_payload_len(db) >= AMD_VSDB_V3_PAYLOAD_MIN_LEN &&
> +		cea_db_payload_len(db) >= AMD_VSDB_V1_PAYLOAD_LEN &&
>  		cea_db_payload_len(db) <= AMD_VSDB_V3_PAYLOAD_MAX_LEN;

[Severity: Medium]
Will this hard limit at AMD_VSDB_V3_PAYLOAD_MAX_LEN (21 bytes) prevent the
intended forward compatibility for future VSDB versions?

The commit message notes that versions > 3 will be parsed as if they were
version 3 because future versions will likely be backwards compatible. 
However, if a future version introduces new fields and the payload exceeds
21 bytes, cea_db_is_amd_vsdb() will return false.

Doesn't this mean the block will be completely ignored before it can ever
reach the fallback logic in drm_parse_amd_vsdb()?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260804143339.714548-1-Alex.Huang2@amd.com?part=1