drm/edid: parse HDMI 2.1 gaming (ALLM/VRR) capabilities from HF-VSDB

Parse the HDMI 2.1 gaming-related capabilities advertised in the HDMI
Forum VSDB (HF-VSDB) and expose them through struct drm_hdmi_info so
drivers can consume them.

Add struct drm_hdmi_vrr_cap describing the sink's VRR capabilities: Fast
VActive (Quick Frame Transport), Negative M VRR, Cinema VRR, MDelta, and
the VRRmin/VRRmax range, together with a "supported" flag derived from
that range. Add the fapa_start_location and allm (Auto Low Latency Mode)
flags to struct drm_hdmi_info.

drm_parse_hdmi_gaming_info() reads byte 8 of the HF-VSDB for the
FAPA/ALLM/FVA/CNMVRR/CinemaVRR/MDelta flags and bytes 9-10 for
VRRmin/VRRmax. Per HDMI 2.1, VRR is considered supported when VRRmin is
within 1-48 and VRRmax is either 0 (maximum based on the video mode) or
>= 100. It is invoked from drm_parse_hdmi_forum_scds(), and the parsed
values are logged for debugging.

Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>
Tested-by: Bernhard Berger <bernhard.berger@gmail.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patch.msgid.link/20260730171754.704049-2-jerry.zuo@amd.com

1 files changed, 47 insertions, 0 deletions

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 48059e7073e5..c61345e6fb08 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -255,6 +255,44 @@ struct drm_scdc {
 };
 
 /**
+ * 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 {
+	/** @fva: flag for Fast VActive (Quick Frame Transport) support */
+	bool fva;
+
+	/** @mcnmvrr: flag for Negative M VRR support */
+	bool cnmvrr;
+
+	/** @mcinema_vrr: flag for Cinema VRR support */
+	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
  *
  * Describes the DSC support provided by HDMI 2.1 sink.
@@ -330,6 +368,15 @@ 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;
+
+	/** @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;
 };