drm/nouveau: Intercept ACPI_VIDEO_NOTIFY_PROBE

Various notebooks with nvidia GPUs generate an ACPI_VIDEO_NOTIFY_PROBE
acpi-video event when an external device gets plugged in (and again on
modesets on that connector), the default behavior in the acpi-video
driver for this is to send a KEY_SWITCHVIDEOMODE evdev event, which
causes e.g. gnome-settings-daemon to ask us to rescan the connectors
(good), but also causes g-s-d to switch to mirror mode on a newly plugged
monitor rather then using the monitor to extend the desktop (bad)
as KEY_SWITCHVIDEOMODE is supposed to switch between extend the desktop
vs mirror mode.

More troublesome are the repeated ACPI_VIDEO_NOTIFY_PROBE events on
changing the mode on the connector, which cause g-s-d to switch
between mirror/extend mode, which causes a new ACPI_VIDEO_NOTIFY_PROBE
event and we end up with an endless loop.

This commit fixes this by adding an acpi notifier block handler to
nouveau_display.c to intercept ACPI_VIDEO_NOTIFY_PROBE and:

1) Wake-up runtime suspended GPUs and call drm_helper_hpd_irq_event()
   on them, this is necessary in some cases for the GPU to detect connector
   hotplug events while runtime suspended
2) Return NOTIFY_BAD to stop acpi-video from emitting a bogus
   KEY_SWITCHVIDEOMODE key-press event

There already is another acpi notifier block handler registered in
drivers/gpu/drm/nouveau/nvkm/engine/device/acpi.c, but that is not
suitable since that one gets unregistered on runtime suspend, and
we also want to intercept ACPI_VIDEO_NOTIFY_PROBE when runtime suspended.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 4cd47bae73c7..ae1fd641c96e 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -37,6 +37,8 @@
  *      - implemented limited ABI16/NVIF interop
  */
 
+#include <linux/notifier.h>
+
 #include <nvif/client.h>
 #include <nvif/device.h>
 #include <nvif/ioctl.h>
@@ -161,6 +163,10 @@ struct nouveau_drm {
 	struct nvbios vbios;
 	struct nouveau_display *display;
 	struct backlight_device *backlight;
+#ifdef CONFIG_ACPI
+	struct notifier_block acpi_nb;
+	struct work_struct acpi_work;
+#endif
 
 	/* power management */
 	struct nouveau_hwmon *hwmon;