[PATCH] drm/amd/display: Set default brightness according to ACPI

[Mario Limonciello]

Currently, amdgpu will always set up the brightness at 100% when it
loads.  However this is jarring when the BIOS has it previously
programmed to a much lower value.

The ACPI ATIF method includes two members for "ac_level" and "dc_level".
These represent the default values that should be used if the system is
brought up in AC and DC respectively.

Use these values to set up the default brightness when the backlight
device is registered.

Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c          |  4 ++++
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 12 +++++++++++-
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  8 ++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
index 7099ff9cf8c5..f85ace0384d2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -383,6 +383,8 @@ static int amdgpu_atif_query_backlight_caps(struct amdgpu_atif *atif)
 			characteristics.min_input_signal;
 	atif->backlight_caps.max_input_signal =
 			characteristics.max_input_signal;
+	atif->backlight_caps.ac_level = characteristics.ac_level;
+	atif->backlight_caps.dc_level = characteristics.dc_level;
 out:
 	kfree(info);
 	return err;
@@ -1268,6 +1270,8 @@ void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps)
 	caps->caps_valid = atif->backlight_caps.caps_valid;
 	caps->min_input_signal = atif->backlight_caps.min_input_signal;
 	caps->max_input_signal = atif->backlight_caps.max_input_signal;
+	caps->ac_level = atif->backlight_caps.ac_level;
+	caps->dc_level = atif->backlight_caps.dc_level;
 }
 
 /**
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 5fd7210b2479..71aa0c518951 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -77,6 +77,7 @@
 #include <linux/types.h>
 #include <linux/pm_runtime.h>
 #include <linux/pci.h>
+#include <linux/power_supply.h>
 #include <linux/firmware.h>
 #include <linux/component.h>
 #include <linux/dmi.h>
@@ -4321,6 +4322,7 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
 	struct drm_device *drm = aconnector->base.dev;
 	struct amdgpu_display_manager *dm = &drm_to_adev(drm)->dm;
 	struct backlight_properties props = { 0 };
+	struct amdgpu_dm_backlight_caps caps = { 0 };
 	char bl_name[16];
 
 	if (aconnector->bl_idx == -1)
@@ -4333,8 +4335,16 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
 		return;
 	}
 
+	amdgpu_acpi_get_backlight_caps(&caps);
+	if (caps.caps_valid) {
+		if (power_supply_is_system_supplied() > 0)
+			props.brightness = caps.ac_level;
+		else
+			props.brightness = caps.dc_level;
+	} else
+		props.brightness = AMDGPU_MAX_BL_LEVEL;
+
 	props.max_brightness = AMDGPU_MAX_BL_LEVEL;
-	props.brightness = AMDGPU_MAX_BL_LEVEL;
 	props.type = BACKLIGHT_RAW;
 
 	snprintf(bl_name, sizeof(bl_name), "amdgpu_bl%d",
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index b246e82f5b0d..df72cb71e95a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -173,6 +173,14 @@ struct amdgpu_dm_backlight_caps {
 	 * @aux_support: Describes if the display supports AUX backlight.
 	 */
 	bool aux_support;
+	/**
+	 * @ac_level: the default brightness if booted on AC
+	 */
+	u8 ac_level;
+	/**
+	 * @dc_level: the default brightness if booted on DC
+	 */
+	u8 dc_level;
 };
 
 /**
-- 
2.43.0