[PATCH 04/14] drm/radeon: Don't register backlight when another backlight should be used

[Hans de Goede <hdegoede@redhat.com>]

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 <hdegoede@redhat.com>
---
 drivers/gpu/drm/Kconfig                         | 1 +
 drivers/gpu/drm/radeon/atombios_encoders.c      | 7 +++++++
 drivers/gpu/drm/radeon/radeon_legacy_encoders.c | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index ddbeb2124df7..37205953056b 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -258,6 +258,7 @@ config DRM_RADEON
 	select HWMON
 	select BACKLIGHT_CLASS_DEVICE
 	select INTERVAL_TREE
+	select ACPI_VIDEO if ACPI && X86 && INPUT
 	help
 	  Choose this option if you have an ATI Radeon graphics card.  There
 	  are both PCI and AGP versions.  You don't need to choose this to
diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
index 70bd84b7ef2b..f82577dc25e8 100644
--- a/drivers/gpu/drm/radeon/atombios_encoders.c
+++ b/drivers/gpu/drm/radeon/atombios_encoders.c
@@ -32,6 +32,8 @@
 #include <drm/drm_file.h>
 #include <drm/radeon_drm.h>
 
+#include <acpi/video.h>
+
 #include "atom.h"
 #include "radeon_atombios.h"
 #include "radeon.h"
@@ -211,6 +213,11 @@ void radeon_atom_backlight_init(struct radeon_encoder *radeon_encoder,
 	if (!(rdev->mode_info.firmware_flags & ATOM_BIOS_INFO_BL_CONTROLLED_BY_GPU))
 		return;
 
+	if (acpi_video_get_backlight_type(true) != acpi_backlight_native) {
+		DRM_INFO("Skipping radeon atom DIG backlight registration\n");
+		return;
+	}
+
 	pdata = kmalloc(sizeof(struct radeon_backlight_privdata), GFP_KERNEL);
 	if (!pdata) {
 		DRM_ERROR("Memory allocation failed\n");
diff --git a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
index 7fdb77d48d6a..d2180f5c80fa 100644
--- a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
+++ b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
@@ -33,6 +33,8 @@
 #include <drm/drm_util.h>
 #include <drm/radeon_drm.h>
 
+#include <acpi/video.h>
+
 #include "radeon.h"
 #include "radeon_asic.h"
 #include "radeon_legacy_encoders.h"
@@ -389,6 +391,11 @@ void radeon_legacy_backlight_init(struct radeon_encoder *radeon_encoder,
 		return;
 #endif
 
+	if (acpi_video_get_backlight_type(true) != acpi_backlight_native) {
+		DRM_INFO("Skipping radeon legacy LVDS backlight registration\n");
+		return;
+	}
+
 	pdata = kmalloc(sizeof(struct radeon_backlight_privdata), GFP_KERNEL);
 	if (!pdata) {
 		DRM_ERROR("Memory allocation failed\n");
-- 
2.36.0