[02/14] drm/i915: Don't register backlight when another backlight should be used

Commit Message

Hans de Goede May 17, 2022, 3:23 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/i915/display/intel_backlight.c | 7 +++++++
 1 file changed, 7 insertions(+)

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c b/drivers/gpu/drm/i915/display/intel_backlight.c
index 98f7ea44042f..582d7f48575d 100644
--- a/drivers/gpu/drm/i915/display/intel_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_backlight.c
@@ -6,6 +6,8 @@ 
 #include <linux/kernel.h>
 #include <linux/pwm.h>
 
+#include <acpi/video.h>
+
 #include "intel_backlight.h"
 #include "intel_connector.h"
 #include "intel_de.h"
@@ -948,6 +950,11 @@  int intel_backlight_device_register(struct intel_connector *connector)
 
 	WARN_ON(panel->backlight.max == 0);
 
+	if (acpi_video_get_backlight_type(true) != acpi_backlight_native) {
+		DRM_INFO("Skipping intel_backlight registration\n");
+		return 0;
+	}
+
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_RAW;