[PATCH] drm/probe-helper: Cancel previous job before starting new one

[PATCH] drm/probe-helper: Cancel previous job before starting new one

[Maxime Ripard]

From: Dom Cobley <popcornmix@gmail.com>

Currently we schedule a call to output_poll_execute from
drm_kms_helper_poll_enable for 10s in future. Later we try to replace
that in drm_helper_probe_single_connector_modes with a 0s schedule with
delayed_event set.

But as there is already a job in the queue this fails, and the immediate
job we wanted with delayed_event set doesn't occur until 10s later.

And that call acts as if connector state has changed, reprobing modes.
This has a side effect of waking up a display that has been blanked.

Make sure we cancel the old job before submitting the immediate one.

Fixes: 162b6a57ac50 ("drm/probe-helper: don't lose hotplug event")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/drm_probe_helper.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 8127be134c39..db954adb446a 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -589,9 +589,11 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 		 * disable itself again.
 		 */
 		dev->mode_config.delayed_event = true;
-		if (dev->mode_config.poll_enabled)
+		if (dev->mode_config.poll_enabled) {
+			cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
 			schedule_delayed_work(&dev->mode_config.output_poll_work,
 					      0);
+		}
 	}
 
 	/* Re-enable polling in case the global poll config changed. */
-- 
2.39.1

Re: (subset) [PATCH] drm/probe-helper: Cancel previous job before starting new one

[Maxime Ripard]

On Fri, 27 Jan 2023 16:40:52 +0100, Maxime Ripard wrote:
> Currently we schedule a call to output_poll_execute from
> drm_kms_helper_poll_enable for 10s in future. Later we try to replace
> that in drm_helper_probe_single_connector_modes with a 0s schedule with
> delayed_event set.
> 
> But as there is already a job in the queue this fails, and the immediate
> job we wanted with delayed_event set doesn't occur until 10s later.
> 
> [...]

Applied to drm/drm-misc (drm-misc-next).

Thanks!
Maxime