On Wed, Aug 01, 2018 at 05:14:58PM -0400, Lyude Paul wrote:
We can't and don't need to try resuming the device from our hotplug handlers, but hotplug events are generally something we'd like to keep the device awake for whenever possible. So, grab a PM ref safely in our hotplug handlers using pm_runtime_get_noresume() and mark the device as busy once we're finished.
Patch looks fine in principle, but doesn't seem to be sufficient to fix the following race:
1. runtime_suspend commences 2. user plugs in a display before the runtime_suspend worker disables hotplug interrupts in nouveau_display_fini() 3. hotplug is handled, display is lit up 4. runtime_suspend worker waits for hotplug handler to finish 5. GPU is runtime suspended and the newly plugged in display goes black
The call to pm_runtime_mark_last_busy() has no effect in this situation because rpm_suspend() doesn't look at the last_busy variable after the call to rpm_callback(). What's necessary here is that runtime_suspend is aborted and -EBUSY returned.
Thanks,
Lukas
Signed-off-by: Lyude Paul lyude@redhat.com Cc: stable@vger.kernel.org Cc: Lukas Wunner lukas@wunner.de Cc: Karol Herbst karolherbst@gmail.com
drivers/gpu/drm/nouveau/nouveau_connector.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c index 8409c3f2c3a1..5a8e8c1ad647 100644 --- a/drivers/gpu/drm/nouveau/nouveau_connector.c +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c @@ -1152,6 +1152,11 @@ nouveau_connector_hotplug(struct nvif_notify *notify) const char *name = connector->name; struct nouveau_encoder *nv_encoder;
/* Resuming the device here isn't possible; but the suspend PM ops
* will wait for us to finish our work before disabling us so this* should be enough*/pm_runtime_get_noresume(drm->dev->dev); nv_connector->hpd_task = current;
if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) {
@@ -1171,6 +1176,9 @@ nouveau_connector_hotplug(struct nvif_notify *notify) }
nv_connector->hpd_task = NULL;
- pm_runtime_mark_last_busy(drm->dev->dev);
- pm_runtime_put_autosuspend(drm->dev->dev); return NVIF_NOTIFY_KEEP;
}
-- 2.17.1