linux-kernel - [PATCH 06/17] drm/amd/display: Add PCON VRR ID check override

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Message-ID: <20260119011146.62302-7-tomasz.pakula.oficjalny@gmail.com>
Date: Mon, 19 Jan 2026 02:11:35 +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 06/17] drm/amd/display: Add PCON VRR ID check override

[Why]
It's currently very hard to test if a random PCON supports VRR and
report it's ID.

[How]
Adds override as part of dc debug mask. Allows faster testing and
reporting of VRR-compatible DP->HDMI adapters.

Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c         | 6 +++++-
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 8 +++++++-
 drivers/gpu/drm/amd/display/dc/dc.h                       | 1 +
 drivers/gpu/drm/amd/display/dc/dm_helpers.h               | 2 +-
 drivers/gpu/drm/amd/include/amd_shared.h                  | 6 ++++++
 5 files changed, 20 insertions(+), 3 deletions(-)

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 662f51faf949..859e34235769 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -2062,6 +2062,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	if (amdgpu_dc_debug_mask & DC_SKIP_DETECTION_LT)
 		adev->dm.dc->debug.skip_detection_link_training = true;
 
+	if (amdgpu_dc_debug_mask & DC_OVERRIDE_PCON_VRR_ID_CHECK)
+		adev->dm.dc->debug.override_pcon_vrr_id_check = true;
+
 	adev->dm.dc->debug.visual_confirm = amdgpu_dc_visual_confirm;
 
 	/* TODO: Remove after DP2 receiver gets proper support of Cable ID feature */
@@ -13279,7 +13282,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 	if (amdgpu_dm_connector->dc_link) {
 		dpcd_caps = amdgpu_dm_connector->dc_link->dpcd_caps;
 		is_pcon = dpcd_caps.dongle_type == DISPLAY_DONGLE_DP_HDMI_CONVERTER;
-		pcon_allowed = dm_helpers_is_vrr_pcon_allowed(amdgpu_dm_connector->dc_link);
+		pcon_allowed = dm_helpers_is_vrr_pcon_allowed(
+			amdgpu_dm_connector->dc_link, connector->dev);
 	}
 
 	/* Some eDP panels only have the refresh rate range info in DisplayID */
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 76a10fe8d545..2ef515a4e1c4 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -1375,7 +1375,7 @@ void dm_helpers_dp_mst_update_branch_bandwidth(
 	// TODO
 }
 
-bool dm_helpers_is_vrr_pcon_allowed(const struct dc_link *link)
+bool dm_helpers_is_vrr_pcon_allowed(const struct dc_link *link, const struct drm_device *dev)
 {
 	if (link->dpcd_caps.dongle_type != DISPLAY_DONGLE_DP_HDMI_CONVERTER)
 		return false;
@@ -1393,6 +1393,12 @@ bool dm_helpers_is_vrr_pcon_allowed(const struct dc_link *link)
 		return true;
 	}
 
+	if (link->dc->debug.override_pcon_vrr_id_check) {
+		drm_info(dev, "Overriding VRR PCON check for ID: 0x%06x\n",
+			 link->dpcd_caps.branch_dev_id);
+		return true;
+	}
+
 	return false;
 }
 
diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 4068d5baef21..5be0507f8a27 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -1056,6 +1056,7 @@ struct dc_debug_options {
 	bool scl_reset_length10;
 	bool hdmi20_disable;
 	bool skip_detection_link_training;
+	bool override_pcon_vrr_id_check;
 	uint32_t edid_read_retry_times;
 	unsigned int force_odm_combine; //bit vector based on otg inst
 	unsigned int seamless_boot_odm_combine;
diff --git a/drivers/gpu/drm/amd/display/dc/dm_helpers.h b/drivers/gpu/drm/amd/display/dc/dm_helpers.h
index f8b45a09d680..ea94c52d2b87 100644
--- a/drivers/gpu/drm/amd/display/dc/dm_helpers.h
+++ b/drivers/gpu/drm/amd/display/dc/dm_helpers.h
@@ -222,7 +222,7 @@ int dm_helpers_dmub_set_config_sync(struct dc_context *ctx,
 
 enum dc_edid_status dm_helpers_get_sbios_edid(struct dc_link *link, struct dc_edid *edid);
 
-bool dm_helpers_is_vrr_pcon_allowed(const struct dc_link *link);
+bool dm_helpers_is_vrr_pcon_allowed(const struct dc_link *link, const struct drm_device *dev);
 bool dm_helpers_is_fullscreen(struct dc_context *ctx, struct dc_stream_state *stream);
 bool dm_helpers_is_hdr_on(struct dc_context *ctx, struct dc_stream_state *stream);
 
diff --git a/drivers/gpu/drm/amd/include/amd_shared.h b/drivers/gpu/drm/amd/include/amd_shared.h
index ac2d3701e2bd..894e1e738ce0 100644
--- a/drivers/gpu/drm/amd/include/amd_shared.h
+++ b/drivers/gpu/drm/amd/include/amd_shared.h
@@ -412,6 +412,12 @@ enum DC_DEBUG_MASK {
 	 * @DC_SKIP_DETECTION_LT: (0x200000) If set, skip detection link training
 	 */
 	DC_SKIP_DETECTION_LT = 0x200000,
+
+	/**
+	 * @DC_OVERRIDE_PCON_VRR_ID_CHECK: (0x400000) If set, always return true if checking for
+	 * PCON VRR compatibility and print it's ID in kernel log.
+	 */
+	DC_OVERRIDE_PCON_VRR_ID_CHECK = 0x400000,
 };
 
 enum amd_dpm_forced_level;
-- 
2.52.0