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Message-ID: <20260113214104.146856-2-tomasz.pakula.oficjalny@gmail.com>
Date: Tue, 13 Jan 2026 22:41:02 +0100
From: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
To: alexander.deucher@....com,
maarten.lankhorst@...ux.intel.com,
mripard@...nel.org,
tzimmermann@...e.de,
airlied@...il.com,
simona@...ll.ch,
harry.wentland@....com,
sunpeng.li@....com,
siqueira@...lia.com
Cc: dri-devel@...ts.freedesktop.org,
amd-gfx@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/3] drm/edid: parse more info from HDMI Forum vsdb
Adds flags and a struct to hold HDMI VRR information. `supported` here
is an additional property which allows easier parsing in consumers and
adds a bit of logic used to detect malformed VRRmin/VRRmax values.
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
Tested-by: Bernhard Berger <bernhard.berger@...il.com>
---
drivers/gpu/drm/drm_edid.c | 41 +++++++++++++++++++++++++++++++-
include/drm/drm_connector.h | 47 +++++++++++++++++++++++++++++++++++++
2 files changed, 87 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index e2e85345aa9a..1e066d614da7 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -6149,6 +6149,33 @@ static void drm_parse_ycbcr420_deep_color_info(struct drm_connector *connector,
hdmi->y420_dc_modes = dc_mask;
}
+static void drm_parse_vrr_info(struct drm_hdmi_info *hdmi, const u8 *db)
+{
+ struct drm_hdmi_vrr_cap *vrr = &hdmi->vrr_cap;
+
+ if (cea_db_payload_len(db) < 8)
+ return;
+
+ hdmi->fapa_start_location = db[8] & DRM_EDID_FAPA_START_LOCATION;
+ hdmi->allm = db[8] & DRM_EDID_ALLM;
+ hdmi->fva = db[8] & DRM_EDID_FVA;
+ vrr->cnmvrr = db[8] & DRM_EDID_CNMVRR;
+ vrr->cinema_vrr = db[8] & DRM_EDID_CINEMA_VRR;
+ vrr->mdelta = db[8] & DRM_EDID_MDELTA;
+
+ if (cea_db_payload_len(db) < 9)
+ return;
+
+ vrr->vrr_min = db[9] & DRM_EDID_VRR_MIN_MASK;
+ vrr->supported = (vrr->vrr_min >= 1 && vrr->vrr_min <= 48);
+
+ if (cea_db_payload_len(db) < 10)
+ return;
+
+ vrr->vrr_max = (db[9] & DRM_EDID_VRR_MAX_UPPER_MASK) << 2 | db[10];
+ vrr->supported &= (vrr->vrr_max == 0 || vrr->vrr_max >= 100);
+}
+
static void drm_parse_dsc_info(struct drm_hdmi_dsc_cap *hdmi_dsc,
const u8 *hf_scds)
{
@@ -6274,7 +6301,7 @@ static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
}
drm_parse_ycbcr420_deep_color_info(connector, hf_scds);
-
+ drm_parse_vrr_info(&connector->display_info.hdmi, hf_scds);
if (cea_db_payload_len(hf_scds) >= 11 && hf_scds[11]) {
drm_parse_dsc_info(hdmi_dsc, hf_scds);
dsc_support = true;
@@ -6284,6 +6311,18 @@ static void drm_parse_hdmi_forum_scds(struct drm_connector *connector,
"[CONNECTOR:%d:%s] HF-VSDB: max TMDS clock: %d KHz, HDMI 2.1 support: %s, DSC 1.2 support: %s\n",
connector->base.id, connector->name,
max_tmds_clock, str_yes_no(max_frl_rate), str_yes_no(dsc_support));
+ drm_dbg_kms(connector->dev,
+ "[CONNECTOR:%d:%s] FAPA in blanking: %s, ALLM support: %s, Fast Vactive support: %s\n",
+ connector->base.id, connector->name, str_yes_no(hdmi->fapa_start_location),
+ str_yes_no(hdmi->allm), str_yes_no(hdmi->fva));
+ drm_dbg_kms(connector->dev,
+ "[CONNECTOR:%d:%s] Negative M VRR support: %s, CinemaVRR support: %s, Mdelta: %d\n",
+ connector->base.id, connector->name, str_yes_no(hdmi->vrr_cap.cnmvrr),
+ str_yes_no(hdmi->vrr_cap.cinema_vrr), hdmi->vrr_cap.mdelta);
+ drm_dbg_kms(connector->dev,
+ "[CONNECTOR:%d:%s] VRRmin: %u, VRRmax: %u, VRR supported: %s\n",
+ connector->base.id, connector->name, hdmi->vrr_cap.vrr_min,
+ hdmi->vrr_cap.vrr_max, str_yes_no(hdmi->vrr_cap.supported));
}
static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 8f34f4b8183d..296f26551206 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -254,6 +254,41 @@ struct drm_scdc {
struct drm_scrambling scrambling;
};
+/**
+ * struct drm_hdmi_vrr_cap - Information about VRR capabilities of a HDMI sink
+ *
+ * Describes the VRR support provided by HDMI 2.1 sink. The information is
+ * fetched fom additional HFVSDB blocks defined for HDMI 2.1.
+ */
+struct drm_hdmi_vrr_cap {
+ /** @mcnmvrr: flag for Negative M VRR support by sink */
+ bool cnmvrr;
+
+ /** @mcinema_vrr: flag for Cinema VRR support by sink */
+ bool cinema_vrr;
+
+ /** @mdelta: flag for limited frame-to-frame compensation support */
+ bool mdelta;
+
+ /**
+ * @vrr_min : minimum supported variable refresh rate in Hz.
+ * Valid values only inide 1 - 48 range
+ */
+ u16 vrr_min;
+
+ /**
+ * @vrr_max : maximum supported variable refresh rate in Hz (optional).
+ * Valid values are either 0 (max based on video mode) or >= 100
+ */
+ u16 vrr_max;
+
+ /**
+ * @supported: flag for vrr support based on checking for VRRmin and
+ * VRRmax values having correct values.
+ */
+ bool supported;
+};
+
/**
* struct drm_hdmi_dsc_cap - DSC capabilities of HDMI sink
*
@@ -330,6 +365,18 @@ struct drm_hdmi_info {
/** @max_lanes: supported by sink */
u8 max_lanes;
+ /** @fapa_start_location: flag for the FAPA in blanking support */
+ bool fapa_start_location;
+
+ /** @allm: flag for Auto Low Latency Mode support by sink */
+ bool allm;
+
+ /** @fva: flag for Fast Vactive support by sink */
+ bool fva;
+
+ /** @vrr_cap: VRR capabilities of the sink */
+ struct drm_hdmi_vrr_cap vrr_cap;
+
/** @dsc_cap: DSC capabilities of the sink */
struct drm_hdmi_dsc_cap dsc_cap;
};
--
2.52.0
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