[PATCH 3.16 224/328] drm/nouveau/drm/nouveau: Use pm_runtime_get_noresume() in connector_detect()

Ben Hutchings
2018-12-09T21:58:31Z

From: Lyude Paul <lyude@redhat.com>

commit 6833fb1ec120bf078e1a527c573a09d4de286224 upstream.

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: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/gpu/drm/nouveau/nouveau_connector.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -256,12 +256,16 @@ nouveau_connector_detect(struct drm_conn
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;
}
@@ -332,10 +336,8 @@ 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;
}