[PATCH 2/2] drm/i915/dp_mst: Fix ww mutex lock failure in for_each_joiner_candidate() loop

[Imre Deak <imre.deak@intel.com>]

Handle modeset WW mutex lock failures due to contention properly.
Return -EDEADLK to the caller instead of attempting to lock the same
mutex again in a subsequent joiner candidate iteration, where the WW
mutex is already in a contended state.

This fixes the following warning:

WARNING: drivers/gpu/drm/drm_modeset_lock.c:298 at modeset_lock+0x1c0/0x210

triggered by ctx->contended.

Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Fixes: b506a8e18c972 ("drm/i915/dp_mst: Rework pipe joiner logic in compute_config")
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index f833f47643271..94c0231426642 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -729,7 +729,7 @@ static int mst_stream_compute_config(struct intel_encoder *encoder,
 							       pipe_config,
 							       conn_state,
 							       num_joined_pipes);
-		if (ret == 0)
+		if (ret == 0 || ret == -EDEADLK)
 			break;
 	}
 
-- 
2.49.1