@@ -391,3 +391,8 @@ bool nouveau_acpi_video_backlight_use_native(void)
{
return acpi_video_backlight_use_native();
}
+
+void nouveau_acpi_video_register_backlight(void)
+{
+ acpi_video_register_backlight();
+}
@@ -12,6 +12,7 @@ void nouveau_unregister_dsm_handler(void);
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; };
@@ -20,6 +21,7 @@ static inline void nouveau_unregister_dsm_handler(void) {}
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
@@ -436,6 +436,13 @@ nouveau_backlight_init(struct drm_connector *connector)
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;
}
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 Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- drivers/gpu/drm/nouveau/nouveau_acpi.c | 5 +++++ drivers/gpu/drm/nouveau/nouveau_acpi.h | 2 ++ drivers/gpu/drm/nouveau/nouveau_backlight.c | 7 +++++++ 3 files changed, 14 insertions(+)