FAILED: patch "[PATCH] drm/amd/display: set allow_freesync before validating a new stream" failed to apply to 6.6-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x ab18dd3061eb2d92e60c8bbf9a435c25962e449f
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261109201429-failed-6.6-ab18dd3061eb@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From ab18dd3061eb2d92e60c8bbf9a435c25962e449f Mon Sep 17 00:00:00 2001
From: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Date: Mon, 26 Oct 2026 12:33:45 +0500
Subject: [PATCH] drm/amd/display: set allow_freesync before validating a new
 stream

After resume from S3, DC enables SubVP on a single FreeSync display at
a high refresh rate, although dcn32_allow_subvp_high_refresh_rate() is
meant to keep SubVP off that configuration ("For single display cases,
freesync must be disabled").  On an RX 7900 XTX driving a FreeSync TV
at 3840x2160@120, amdgpu_dm_capabilities reports sub-viewport disabled
after boot and enabled after "rtcwake -m mem", and the memory clock
starts switching.  It stays that way until a later commit re-validates
the state; a CRTC gamma change (toggling Night Light) turns SubVP off
again.

The policy reads dc_stream_state::allow_freesync while the new state
is validated, but amdgpu_dm sets that field only in
amdgpu_dm_update_freesync_state_on_stream(), on the first flip after
the commit.  A stream created by a modeset is therefore validated as
if FreeSync were off.  On resume, dm_destroy_cached_state() drops the
streams and forces a modeset, so the resumed state is validated
without FreeSync.

Set allow_freesync in amdgpu_dm_get_freesync_config_for_crtc(), which
atomic check calls for every active CRTC and which already writes
ignore_msa_timing_param to the stream.  It uses vrr_supported, the
condition the flip-time value is derived from.  With this change the
same TV keeps SubVP disabled across "rtcwake -m mem".

On this machine SubVP is also what exposes the single-frame scanout
corruption reported in the thread linked below, so the FreeSync
setting stopped working as a workaround after every suspend.

Fixes: 87f0c16e0eeb ("drm/amd/display: Enable SubVP for high refresh rate displays")
Link: https://lore.kernel.org/all/20260829010525.29935-1-mikhail.v.gavrilov@gmail.com/
Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5714#note_3736349
Tested-by: Josh Kasten <jkasten@gmail.com>
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 29793918b0eb63b6810b248a906f87dd79b70be5)
Cc: stable@vger.kernel.org
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c    | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c
index ab9cfbce8d73c..4620135437c5e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_freesync.c
@@ -131,6 +131,14 @@ void amdgpu_dm_get_freesync_config_for_crtc(
 					vrefresh >= aconnector->min_vfreq &&
 					vrefresh <= aconnector->max_vfreq;
 
+	/*
+	 * DC reads allow_freesync while validating the new state, for example
+	 * to keep SubVP off a single FreeSync display, but it is otherwise set
+	 * only on the first flip after the commit.  Set it here, so that a
+	 * stream created by this commit is not validated without it.
+	 */
+	new_crtc_state->stream->allow_freesync = new_crtc_state->vrr_supported;
+
 	if (new_crtc_state->vrr_supported) {
 		new_crtc_state->stream->ignore_msa_timing_param = true;
 		fs_vid_mode = new_crtc_state->freesync_config.state == VRR_STATE_ACTIVE_FIXED;
-- 
2.53.0