[PATCH 1/3] drm/i915/vrr: Avoid vrr for PCON with HDMI2.1 sink

[Ankit Nautiyal <ankit.k.nautiyal@intel.com>]

Currently we do not support VRR with HDMI so skip vrr compute
config step for all DP branch devices.

v2: Restrict VRR on all DP branch devices instead for checking only for
    HDMI. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_vrr.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index fae1186a90b2..1b09992ce9fd 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -55,6 +55,16 @@ bool intel_vrr_is_capable(struct intel_connector *connector)
 		if (connector->mst.dp)
 			return false;
 		intel_dp = intel_attached_dp(connector);
+		/*
+		 * Among non-MST DP branch devices, only an HDMI 2.1 sink connected
+		 * via a PCON could support VRR. However, supporting VRR through a
+		 * PCON requires non-trivial changes that are not implemented yet.
+		 * Until that support exists, avoid VRR on all DP branch devices.
+		 *
+		 * TODO: Add support for VRR for DP->HDMI 2.1 PCON.
+		 */
+		if (drm_dp_is_branch(intel_dp->dpcd))
+			return false;
 
 		if (!drm_dp_sink_can_do_video_without_timing_msa(intel_dp->dpcd))
 			return false;
-- 
2.45.2