[PATCH v2] drm: Schedule the output_poll_work with 1s delay if we have delayed event

[Peter Ujfalusi]

Instead of scheduling the work to handle the initial delayed event, use 1s
delay.

This delay should not be needed, but Optimus/nouveau will fail in a
mysterious way if the delayed event is handled as soon as possible like it
is done in drm_helper_probe_single_connector_modes() in case the poll
was enabled before.

Reverting 339fd36238dd would give back the 10 sec (!) delay to handle the
delayed event. Adding 1sec delay to the poll_work is enough to work around
the issue in Optimus setups and gives shorter response on handling the
initial delayed event.

Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling")
Cc: stable at vger.kernel.org   # v4.9
Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
---
 drivers/gpu/drm/drm_probe_helper.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 06a62e37fbdc..258abed43e38 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -146,8 +146,16 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev)
 	drm_connector_list_iter_put(&conn_iter);
 
 	if (dev->mode_config.delayed_event) {
+		/*
+		 * Use short (1s) delay to handle the initial delayed event.
+		 * This delay should not be needed, but Optimus/nouveau will
+		 * fail in a mysterious way if the delayed event is handled as
+		 * soon as possible like it is done in
+		 * drm_helper_probe_single_connector_modes() in case the poll
+		 * was enabled before.
+		 */
 		poll = true;
-		delay = 0;
+		delay = HZ;
 	}
 
 	if (poll)
-- 
2.11.0