Patch "drm: Schedule the output_poll_work with 1s delay if we have delayed event" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

drm: Schedule the output_poll_work with 1s delay if we have delayed event

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-schedule-the-output_poll_work-with-1s-delay-if-we-have-delayed-event.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Ujfalusi <[email protected]>
Date: Mon, 9 Jan 2017 16:31:58 +0200
Subject: drm: Schedule the output_poll_work with 1s delay if we have delayed event

From: Peter Ujfalusi <[email protected]>

commit 68f458eec7069d618a6c884ca007426e0cea411b upstream.

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.

---
 drivers/gpu/drm/drm_probe_helper.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

@@ -143,8 +143,18 @@ void drm_kms_helper_poll_enable_locked(s
 	}
 
 	if (dev->mode_config.delayed_event) {
+		/*
+		 * FIXME:
+		 *
+		 * 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)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/drm-schedule-the-output_poll_work-with-1s-delay-if-we-have-delayed-event.patch