[PATCH 03/14] drm/amdgpu: 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/amd/amdgpu/atombios_encoders.c    | 7 +++++++
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index f1422bee3dcc..ddbeb2124df7 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -280,6 +280,7 @@ config DRM_AMDGPU
 	select HWMON
 	select BACKLIGHT_CLASS_DEVICE
 	select INTERVAL_TREE
+	select ACPI_VIDEO if ACPI && X86 && INPUT
 	help
 	  Choose this option if you have a recent AMD Radeon graphics card.
 
diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
index a92d86e12718..f9c62cd84a18 100644
--- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
@@ -26,6 +26,8 @@
 
 #include <linux/pci.h>
 
+#include <acpi/video.h>
+
 #include <drm/drm_crtc_helper.h>
 #include <drm/amdgpu_drm.h>
 #include "amdgpu.h"
@@ -186,6 +188,11 @@ void amdgpu_atombios_encoder_init_backlight(struct amdgpu_encoder *amdgpu_encode
 	if (!(adev->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 amdgpu atom DIG backlight registration\n");
+		return;
+	}
+
 	pdata = kmalloc(sizeof(struct amdgpu_backlight_privdata), GFP_KERNEL);
 	if (!pdata) {
 		DRM_ERROR("Memory allocation failed\n");
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 62139ff35476..a838c7b5d942 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -83,6 +83,8 @@
 #include <drm/drm_vblank.h>
 #include <drm/drm_audio_component.h>
 
+#include <acpi/video.h>
+
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 #include "ivsrcid/dcn/irqsrcs_dcn_1_0.h"
 
@@ -4079,6 +4081,11 @@ amdgpu_dm_register_backlight_device(struct amdgpu_display_manager *dm)
 	amdgpu_dm_update_backlight_caps(dm, dm->num_of_edps);
 	dm->brightness[dm->num_of_edps] = AMDGPU_MAX_BL_LEVEL;
 
+	if (acpi_video_get_backlight_type(true) != acpi_backlight_native) {
+		DRM_INFO("Skipping amdgpu DM backlight registration\n");
+		return;
+	}
+
 	props.max_brightness = AMDGPU_MAX_BL_LEVEL;
 	props.brightness = AMDGPU_MAX_BL_LEVEL;
 	props.type = BACKLIGHT_RAW;
-- 
2.36.0