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drm/nouveau/drm/nouveau: Fix bogus drm_kms_helper_poll_enable() placement

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Turns out this part is my fault for not noticing when reviewing
9a2eba337c ("drm/nouveau: Fix drm poll_helper handling"). Currently
we call drm_kms_helper_poll_enable() from nouveau_display_hpd_work().
This makes basically no sense however, because that means we're calling
drm_kms_helper_poll_enable() every time we schedule the hotplug
detection work. This is also against the advice mentioned in
drm_kms_helper_poll_enable()'s documentation:

 Note that calls to enable and disable polling must be strictly ordered,
 which is automatically the case when they're only call from
 suspend/resume callbacks.

Of course, hotplugs can't really be ordered. They could even happen
immediately after we called drm_kms_helper_poll_disable() in
nouveau_display_fini(), which can lead to all sorts of issues.

Additionally; enabling polling /after/ we call
drm_helper_hpd_irq_event() could also mean that we'd miss a hotplug
event anyway, since drm_helper_hpd_irq_event() wouldn't bother trying to
probe connectors so long as polling is disabled.

So; simply move this back into nouveau_display_init() again. The race
condition that both of these patches attempted to work around has
already been fixed properly in

  d61a5c1063 ("drm/nouveau: Fix deadlock on runtime suspend")

Fixes: 9a2eba337c ("drm/nouveau: Fix drm poll_helper handling")
Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
Lyude Paul 2018-08-15 15:00:11 -04:00 committed by Ben Skeggs
parent 5b394b2ddf
commit d77ef138ff
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/gpu/drm/nouveau/nouveau_display.c
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@ -355,8 +355,6 @@ nouveau_display_hpd_work(struct work_struct *work)
pm_runtime_get_sync(drm->dev->dev);
drm_helper_hpd_irq_event(drm->dev);
/* enable polling for external displays */
drm_kms_helper_poll_enable(drm->dev);
pm_runtime_mark_last_busy(drm->dev->dev);
pm_runtime_put_sync(drm->dev->dev);
@ -411,6 +409,11 @@ nouveau_display_init(struct drm_device *dev)
if (ret)
return ret;
/* enable connector detection and polling for connectors without HPD
* support
*/
drm_kms_helper_poll_enable(dev);
/* enable hotplug interrupts */
drm_connector_list_iter_begin(dev, &conn_iter);
nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) {