Typically the acpi_video driver will initialize before nouveau, which
used to cause /sys/class/backlight/acpi_video0 to get registered and then
nouveau would register its own nv_backlight device later. After which
the drivers/acpi/video_detect.c code unregistered the acpi_video0 device
to avoid there being 2 backlight devices.
This means that userspace used to briefly see 2 devices and the
disappearing of acpi_video0 after a brief time confuses the systemd
backlight level save/restore code, see e.g.:
https://bbs.archlinux.org/viewtopic.php?id=269920
To fix this the ACPI video code has been modified to make backlight class
device registration a separate step, relying on the drm/kms driver to
ask for the acpi_video backlight registration after it is done setting up
its native backlight device.
Add a call to the new acpi_video_register_backlight() when native backlight
device registration has failed / was skipped to ensure that there is a
backlight device available before the drm_device gets registered with
userspace.
Changes in v2:
- Add nouveau_acpi_video_register_backlight() wrapper to avoid unresolved
symbol errors on non X86
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
{
return acpi_video_backlight_use_native();
}
+
+void nouveau_acpi_video_register_backlight(void)
+{
+ acpi_video_register_backlight();
+}
void nouveau_switcheroo_optimus_dsm(void);
void *nouveau_acpi_edid(struct drm_device *, struct drm_connector *);
bool nouveau_acpi_video_backlight_use_native(void);
+void nouveau_acpi_video_register_backlight(void);
#else
static inline bool nouveau_is_optimus(void) { return false; };
static inline bool nouveau_is_v1_dsm(void) { return false; };
static inline void nouveau_switcheroo_optimus_dsm(void) {}
static inline void *nouveau_acpi_edid(struct drm_device *dev, struct drm_connector *connector) { return NULL; }
static inline bool nouveau_acpi_video_backlight_use_native(void) { return true; }
+static inline void nouveau_acpi_video_register_backlight(void) {}
#endif
#endif
fail_alloc:
kfree(bl);
+ /*
+ * If we get here we have an internal panel, but no nv_backlight,
+ * try registering an ACPI video backlight device instead.
+ */
+ if (ret == 0)
+ nouveau_acpi_video_register_backlight();
+
return ret;
}