FAILED: patch "[PATCH] drm/display/dp_mst: Fix drm_dp_mst_add_affected_dsc_crtcs()" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-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>.

Possible dependencies:

2f3a1273862c ("drm/display/dp_mst: Fix drm_dp_mst_add_affected_dsc_crtcs() return code")

thanks,

greg k-h

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

From 2f3a1273862cb82cca227630cc7f04ce0c94b6bb Mon Sep 17 00:00:00 2001
From: Lyude Paul <lyude@redhat.com>
Date: Mon, 14 Nov 2022 17:17:53 -0500
Subject: [PATCH] drm/display/dp_mst: Fix drm_dp_mst_add_affected_dsc_crtcs()
 return code

Looks like that we're accidentally dropping a pretty important return code
here. For some reason, we just return -EINVAL if we fail to get the MST
topology state. This is wrong: error codes are important and should never
be squashed without being handled, which here seems to have the potential
to cause a deadlock.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Wayne Lin <Wayne.Lin@amd.com>
Fixes: 8ec046716ca8 ("drm/dp_mst: Add helper to trigger modeset on affected DSC MST CRTCs")
Cc: <stable@vger.kernel.org> # v5.6+
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index ecd22c038c8c..51a46689cda7 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -5186,7 +5186,7 @@ int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm
 	mst_state = drm_atomic_get_mst_topology_state(state, mgr);
 
 	if (IS_ERR(mst_state))
-		return -EINVAL;
+		return PTR_ERR(mst_state);
 
 	list_for_each_entry(pos, &mst_state->payloads, next) {