On some i915 platforms at least the HPD poll work involves I2C bit-banging using udelay()s to probe for monitor EDIDs. This in turn may trigger the workqueue: output_poll_execute [drm_kms_helper] hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND warning. Fix this by scheduling drm_mode_config::output_poll_work on a WQ_UNBOUND workqueue. Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Heiner Kallweit <hkallweit1@xxxxxxxxx> CC: stable@xxxxxxxxxxxxxxx # 6.5 Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Suggested-by: Tejun Heo <tj@xxxxxxxxxx> Suggested-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> Reported-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9245 Link: https://lore.kernel.org/all/f7e21caa-e98d-e5b5-932a-fe12d27fde9b@xxxxxxxxx Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> --- drivers/gpu/drm/drm_probe_helper.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c index 3f479483d7d80..72eac0cd25e74 100644 --- a/drivers/gpu/drm/drm_probe_helper.c +++ b/drivers/gpu/drm/drm_probe_helper.c @@ -279,7 +279,8 @@ static void reschedule_output_poll_work(struct drm_device *dev) */ delay = HZ; - schedule_delayed_work(&dev->mode_config.output_poll_work, delay); + queue_delayed_work(system_unbound_wq, + &dev->mode_config.output_poll_work, delay); } /** @@ -614,7 +615,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector, */ dev->mode_config.delayed_event = true; if (dev->mode_config.poll_enabled) - mod_delayed_work(system_wq, + mod_delayed_work(system_unbound_wq, &dev->mode_config.output_poll_work, 0); } @@ -838,7 +839,8 @@ static void output_poll_execute(struct work_struct *work) drm_kms_helper_hotplug_event(dev); if (repoll) - schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD); + queue_delayed_work(system_unbound_wq, + delayed_work, DRM_OUTPUT_POLL_PERIOD); } /** -- 2.37.2
