@@ -30,6 +30,8 @@
#include <drm/drm_device.h>
#include <drm/radeon_drm.h>
+#include <acpi/video.h>
+
#include "radeon.h"
#include "radeon_atombios.h"
#include "radeon_legacy_encoders.h"
@@ -167,7 +169,7 @@ static void radeon_encoder_add_backlight(struct radeon_encoder *radeon_encoder,
return;
if (radeon_backlight == 0) {
- return;
+ use_bl = false;
} else if (radeon_backlight == 1) {
use_bl = true;
} else if (radeon_backlight == -1) {
@@ -193,6 +195,13 @@ static void radeon_encoder_add_backlight(struct radeon_encoder *radeon_encoder,
else
radeon_legacy_backlight_init(radeon_encoder, connector);
}
+
+ /*
+ * If there is no native backlight device (which may happen even when
+ * use_bl==true) try registering an ACPI video backlight device instead.
+ */
+ if (!rdev->mode_info.bl_encoder)
+ acpi_video_register_backlight();
}
void
Typically the acpi_video driver will initialize before radeon, which used to cause /sys/class/backlight/acpi_video0 to get registered and then radeon would register its own radeon_bl# 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 radeon skips registering its own backlight device because of e.g. the firmware_flags or the acpi_video_get_backlight_type() return value. This ensures that if the acpi_video backlight device should be used, it will be available before the radeon drm_device gets registered with userspace. Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- drivers/gpu/drm/radeon/radeon_encoders.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)