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

commit d77ef138ff572409ab93d492e5e6c826ee6fb21d upstream.

Turns out this part is my fault for not noticing when reviewing
9a2eba337cace ("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

  d61a5c106351 ("drm/nouveau: Fix deadlock on runtime suspend")

Fixes: 9a2eba337cace ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 6526a33660874e7b8d38522a0f0db0e46346be76..b779fd59c34b5ec2df17f6857c1256ceeb4eccb7 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -367,8 +367,6 @@ 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);
@@ -422,6 +420,11 @@ 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 */
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                struct nouveau_connector *conn = nouveau_connector(connector);