[v3,4/5] drm/gma500: Don't register backlight when another backlight should be used

Commit Message

Hans de Goede Sept. 17, 2022, 8:59 p.m. UTC

Before this commit when we want userspace to use the acpi_video backlight
device we register both the GPU's native backlight device and acpi_video's
firmware acpi_video# backlight device. This relies on userspace preferring
firmware type backlight devices over native ones.

Registering 2 backlight devices for a single display really is
undesirable, don't register the GPU's native backlight device when
another backlight device should be used.

Signed-off-by: Hans de Goede <[e-mail]>
---
 drivers/gpu/drm/gma500/backlight.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Patch

diff --git a/drivers/gpu/drm/gma500/backlight.c b/drivers/gpu/drm/gma500/backlight.c
index e85fd181f2f3..577a4987b193 100644
--- a/drivers/gpu/drm/gma500/backlight.c
+++ b/drivers/gpu/drm/gma500/backlight.c
@@ -7,6 +7,8 @@ 
  * Authors: Eric Knopp
  */
 
+#include <acpi/video.h>
+
 #include "psb_drv.h"
 #include "psb_intel_reg.h"
 #include "psb_intel_drv.h"
@@ -80,6 +82,12 @@  int gma_backlight_init(struct drm_device *dev)
 	if (ret)
 		return ret;
 
+	if (!acpi_video_backlight_use_native()) {
+		drm_info(dev, "Skipping %s backlight registration\n",
+			 dev_priv->ops->backlight_name);
+		return 0;
+	}
+
 #ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
 	props.brightness = dev_priv->backlight_level;
 	props.max_brightness = PSB_MAX_BRIGHTNESS;