drm/nouveau/drm/nouveau: Use pm_runtime_get_noresume() in connector_detect()

It's true we can't resume the device from poll workers in
nouveau_connector_detect(). We can however, prevent the autosuspend
timer from elapsing immediately if it hasn't already without risking any
sort of deadlock with the runtime suspend/resume operations. So do that
instead of entirely avoiding grabbing a power reference.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 51932c72334ef6529abb18bc44762cc01ba2d176..31b31a35c8fe589bd94fadc324aee2950595e07d 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -555,12 +555,16 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
                nv_connector->edid = NULL;
        }
 
-       /* Outputs are only polled while runtime active, so acquiring a
-        * runtime PM ref here is unnecessary (and would deadlock upon
-        * runtime suspend because it waits for polling to finish).
+       /* Outputs are only polled while runtime active, so resuming the
+        * device here is unnecessary (and would deadlock upon runtime suspend
+        * because it waits for polling to finish). We do however, want to
+        * prevent the autosuspend timer from elapsing during this operation
+        * if possible.
         */
-       if (!drm_kms_helper_is_poll_worker()) {
-               ret = pm_runtime_get_sync(connector->dev->dev);
+       if (drm_kms_helper_is_poll_worker()) {
+               pm_runtime_get_noresume(dev->dev);
+       } else {
+               ret = pm_runtime_get_sync(dev->dev);
                if (ret < 0 && ret != -EACCES)
                        return conn_status;
        }
@@ -638,10 +642,8 @@ detect_analog:
 
  out:
 
-       if (!drm_kms_helper_is_poll_worker()) {
-               pm_runtime_mark_last_busy(connector->dev->dev);
-               pm_runtime_put_autosuspend(connector->dev->dev);
-       }
+       pm_runtime_mark_last_busy(dev->dev);
+       pm_runtime_put_autosuspend(dev->dev);
 
        return conn_status;
 }