linux-kernel - [PATCH 04/17] drm/amd/display: Use bigger VRR range if found in AMD vsdb

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Message-ID: <20260119011146.62302-5-tomasz.pakula.oficjalny@gmail.com>
Date: Mon, 19 Jan 2026 02:11:33 +0100
From: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
To: alexander.deucher@....com,
	harry.wentland@....com,
	sunpeng.li@....com
Cc: maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	siqueira@...lia.com,
	dri-devel@...ts.freedesktop.org,
	amd-gfx@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	tomasz.pakula.oficjalny@...il.com,
	bernhard.berger@...il.com
Subject: [PATCH 04/17] drm/amd/display: Use bigger VRR range if found in AMD vsdb

[Why]
Some monitors only expose their full VRR range in AMD vsdb for some
reason.

[How]
Compare exposed ranges and use the bigger one.

This check could be merged with the previous one but it's better to keep
them separate to easily convey their meaning.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4177
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 69f3dbfe4ca3..37ab89532408 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -13204,6 +13204,18 @@ static bool copy_range_to_amdgpu_connector(struct drm_connector *conn)
 	return is_freesync_capable(range);
 }
 
+/**
+ * Returns true if range from AMD vsdb is bigger
+ */
+static bool compare_ranges(struct drm_connector *conn,
+			   struct amdgpu_hdmi_vsdb_info *vsdb)
+{
+	struct drm_monitor_range_info *range = &conn->display_info.monitor_range;
+
+	return (vsdb->max_refresh_rate_hz - vsdb->min_refresh_rate_hz) >
+	       (range->max_vfreq - range->min_vfreq);
+}
+
 /**
  * amdgpu_dm_update_freesync_caps - Update Freesync capabilities
  *
@@ -13277,6 +13289,10 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 		if (valid_vsdb_cea && is_monitor_range_invalid(connector))
 			monitor_range_from_vsdb(connector, &vsdb_info);
 
+		/* Use bigger range if found in AMD vsdb */
+		if (valid_vsdb_cea && compare_ranges(connector, &vsdb_info))
+			monitor_range_from_vsdb(connector, &vsdb_info);
+
 		if (dpcd_caps.allow_invalid_MSA_timing_param)
 			freesync_capable = copy_range_to_amdgpu_connector(connector);
 
-- 
2.52.0