linux-kernel - [PATCH 5.8 212/255] drm/dp_mst: Dont return error code when crtc is null

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Date:   Tue,  1 Sep 2020 17:11:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>,
        Lyude Paul <lyude@...hat.com>
Subject: [PATCH 5.8 212/255] drm/dp_mst: Dont return error code when crtc is null

From: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>

commit 88fee1c9007a38c19f2c558dc0ab1ddb4c323dc5 upstream.

[Why]
In certain cases the crtc can be NULL and returning -EINVAL causes
atomic check to fail when it shouln't. This leads to valid
configurations failing because atomic check fails.

[How]
Don't early return if crtc is null

Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>
Reviewed-by: Lyude Paul <lyude@...hat.com>
[added stable cc]
Signed-off-by: Lyude Paul <lyude@...hat.com>
Fixes: 8ec046716ca8 ("drm/dp_mst: Add helper to trigger modeset on affected DSC MST CRTCs")
Cc: <stable@...r.kernel.org> # v5.6+
Link: https://patchwork.freedesktop.org/patch/msgid/20200814170140.24917-1-Bhawanpreet.Lakha@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/drm_dp_mst_topology.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4993,8 +4993,8 @@ int drm_dp_mst_add_affected_dsc_crtcs(st
 
 		crtc = conn_state->crtc;
 
-		if (WARN_ON(!crtc))
-			return -EINVAL;
+		if (!crtc)
+			continue;
 
 		if (!drm_dp_mst_dsc_aux_for_port(pos->port))
 			continue;