drm/nouveau/kms/nv50: fix oops during DP IRQ handling on non-MST boards

Reported-by: Woody Suwalski <terraluna977@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index 2dbf62a2ac41..e4751f92b342 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -3265,11 +3265,14 @@ nv50_mstm = {
 void
 nv50_mstm_service(struct nv50_mstm *mstm)
 {
-        struct drm_dp_aux *aux = mstm->mgr.aux;
+        struct drm_dp_aux *aux = mstm ? mstm->mgr.aux : NULL;
         bool handled = true;
         int ret;
         u8 esi[8] = {};
 
+        if (!aux)
+                return;
+
         while (handled) {
                 ret = drm_dp_dpcd_read(aux, DP_SINK_COUNT_ESI, esi, 8);
                 if (ret != 8) {