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drm/edid: Parse AMD Vendor-Specific Data Block

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Parse the AMD VSDB v3 from CTA extension blocks and store the result
in struct drm_amd_vsdb_info, a new field of drm_display_info. This
includes replay mode, panel type, and luminance ranges.

Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Chenyu Chen
2026-03-31 11:14:26 +08:00
committed by Alex Deucher
parent 57ce498faa
commit 118362a962
2 changed files with 110 additions and 0 deletions
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72
drivers/gpu/drm/drm_edid.c
View File

@@ -99,6 +99,29 @@ enum drm_edid_internal_quirk {
};
#define MICROSOFT_IEEE_OUI 0xca125c
#define AMD_IEEE_OUI 0x00001A
#define AMD_VSDB_V3_PAYLOAD_MIN_LEN 15
#define AMD_VSDB_V3_PAYLOAD_MAX_LEN 20
struct amd_vsdb_v3_payload {
u8 oui[3];
u8 version;
u8 feature_caps;
u8 rsvd0[3];
u8 cs_eotf_support;
u8 lum1_max;
u8 lum1_min;
u8 lum2_max;
u8 lum2_min;
u8 rsvd1[2];
/*
* Bytes beyond AMD_VSDB_V3_PAYLOAD_MIN_LEN are optional; a
* monitor may provide a payload as short as 15 bytes. Always
* check cea_db_payload_len() before accessing extra[].
*/
u8 extra[AMD_VSDB_V3_PAYLOAD_MAX_LEN - AMD_VSDB_V3_PAYLOAD_MIN_LEN];
} __packed;
struct detailed_mode_closure {
struct drm_connector *connector;
@@ -5205,6 +5228,13 @@ static bool cea_db_is_microsoft_vsdb(const struct cea_db *db)
cea_db_payload_len(db) == 21;
}
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_V3_PAYLOAD_MAX_LEN;
}
static bool cea_db_is_vcdb(const struct cea_db *db)
{
return cea_db_is_extended_tag(db, CTA_EXT_DB_VIDEO_CAP) &&
@@ -6401,6 +6431,45 @@ static void drm_parse_microsoft_vsdb(struct drm_connector *connector,
connector->base.id, connector->name, version, db[5]);
}
static void drm_parse_amd_vsdb(struct drm_connector *connector,
const struct cea_db *db)
{
struct drm_display_info *info = &connector->display_info;
const u8 *data = cea_db_data(db);
const struct amd_vsdb_v3_payload *p;
p = (const struct amd_vsdb_v3_payload *)data;
if (p->version != 0x03) {
drm_dbg_kms(connector->dev,
"[CONNECTOR:%d:%s] Unsupported AMD VSDB version %u\n",
connector->base.id, connector->name, p->version);
return;
}
info->amd_vsdb.version = p->version;
info->amd_vsdb.replay_mode = p->feature_caps & 0x40;
info->amd_vsdb.panel_type = (p->cs_eotf_support & 0xC0) >> 6;
info->amd_vsdb.luminance_range1.max_luminance = p->lum1_max;
info->amd_vsdb.luminance_range1.min_luminance = p->lum1_min;
info->amd_vsdb.luminance_range2.max_luminance = p->lum2_max;
info->amd_vsdb.luminance_range2.min_luminance = p->lum2_min;
/*
* The AMD VSDB v3 payload length is variable (15..20 bytes).
* All fields through p->rsvd1 (byte 14) are always present,
* but p->extra[] (bytes 15+) may not be. Any future access to
* extra[] must be guarded with a runtime length check to avoid
* out-of-bounds reads on shorter (but spec-valid) payloads.
* For example:
*
* int len = cea_db_payload_len(db);
*
* if (len > AMD_VSDB_V3_PAYLOAD_MIN_LEN)
* info->amd_vsdb.foo = p->extra[0];
*/
}
static void drm_parse_cea_ext(struct drm_connector *connector,
const struct drm_edid *drm_edid)
{
@@ -6449,6 +6518,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
drm_parse_hdmi_forum_scds(connector, data);
else if (cea_db_is_microsoft_vsdb(db))
drm_parse_microsoft_vsdb(connector, data);
else if (cea_db_is_amd_vsdb(db))
drm_parse_amd_vsdb(connector, db);
else if (cea_db_is_y420cmdb(db))
parse_cta_y420cmdb(connector, db, &y420cmdb_map);
else if (cea_db_is_y420vdb(db))
@@ -6641,6 +6712,7 @@ static void drm_reset_display_info(struct drm_connector *connector)
info->quirks = 0;
info->source_physical_address = CEC_PHYS_ADDR_INVALID;
memset(&info->amd_vsdb, 0, sizeof(info->amd_vsdb));
}
static void update_displayid_info(struct drm_connector *connector,

38
include/drm/drm_connector.h
View File

@@ -693,6 +693,39 @@ enum drm_bus_flags {
DRM_BUS_FLAG_SHARP_SIGNALS = BIT(8),
};
/**
* struct drm_amd_vsdb_info - AMD-specific VSDB information
*
* This structure holds information parsed from the AMD Vendor-Specific Data
* Block (VSDB) version 3.
*/
struct drm_amd_vsdb_info {
/**
* @version: Version of the Vendor-Specific Data Block (VSDB)
*/
u8 version;
/**
* @replay_mode: Panel Replay supported
*/
bool replay_mode;
/**
* @panel_type: Panel technology type
*/
u8 panel_type;
/**
* @luminance_range1: Luminance for max back light
*/
struct drm_luminance_range_info luminance_range1;
/**
* @luminance_range2: Luminance for min back light
*/
struct drm_luminance_range_info luminance_range2;
};
/**
* struct drm_display_info - runtime data about the connected sink
*
@@ -883,6 +916,11 @@ struct drm_display_info {
* Defaults to CEC_PHYS_ADDR_INVALID (0xffff).
*/
u16 source_physical_address;
/**
* @amd_vsdb: AMD-specific VSDB information.
*/
struct drm_amd_vsdb_info amd_vsdb;
};
int drm_display_info_set_bus_formats(struct drm_display_info *info,