linux-kernel - [PATCH v2 2/2] platform/loongarch: laptop: Support backlight power control

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Message-ID: <20250605054828.15093-3-ziyao@disroot.org>
Date: Thu,  5 Jun 2025 05:48:28 +0000
From: Yao Zi <ziyao@...root.org>
To: Huacai Chen <chenhuacai@...nel.org>,
	Jianmin Lv <lvjianmin@...ngson.cn>,
	WANG Xuerui <kernel@...0n.name>
Cc: linux-kernel@...r.kernel.org,
	loongarch@...ts.linux.dev,
	Mingcong Bai <jeffbai@...c.io>,
	Kexy Biscuit <kexybiscuit@...c.io>,
	Yao Zi <ziyao@...root.org>
Subject: [PATCH v2 2/2] platform/loongarch: laptop: Support backlight power control

loongson_laptop_turn_{on,off}_backlight() are designed for controlling
power of the backlight, but they aren't really used in the driver
previously.

Unify these two functions since they only differ in arguments passed to
ACPI method, and wire up loongson_laptop_backlight_update() to update
power state of the backlight as well. Tested on TongFang L860-T2 3A5000
laptop.

Signed-off-by: Yao Zi <ziyao@...root.org>
---
 drivers/platform/loongarch/loongson-laptop.c | 76 ++++++++++----------
 1 file changed, 38 insertions(+), 38 deletions(-)

diff --git a/drivers/platform/loongarch/loongson-laptop.c b/drivers/platform/loongarch/loongson-laptop.c
index 828bd62e3596..fe3f5b24c0a1 100644
--- a/drivers/platform/loongarch/loongson-laptop.c
+++ b/drivers/platform/loongarch/loongson-laptop.c
@@ -56,9 +56,8 @@ static struct input_dev *generic_inputdev;
 static acpi_handle hotkey_handle;
 static struct key_entry hotkey_keycode_map[GENERIC_HOTKEY_MAP_MAX];
 
-int loongson_laptop_turn_on_backlight(void);
-int loongson_laptop_turn_off_backlight(void);
 static int loongson_laptop_backlight_update(struct backlight_device *bd);
+static bool bl_powered;
 
 /* 2. ACPI Helpers and device model */
 
@@ -354,16 +353,41 @@ static int ec_backlight_level(u8 level)
 	return level;
 }
 
+static int ec_backlight_set_power(bool state)
+{
+	int status;
+	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
+	struct acpi_object_list args = { 1, &arg0 };
+
+	arg0.integer.value = state;
+	status = acpi_evaluate_object(NULL, "\\BLSW", &args, NULL);
+	if (ACPI_FAILURE(status)) {
+		pr_info("Loongson lvds error: 0x%x\n", status);
+		return -EIO;
+	}
+
+	return 0;
+}
+
 static int loongson_laptop_backlight_update(struct backlight_device *bd)
 {
-	int lvl = ec_backlight_level(bd->props.brightness);
+	int ret = 0, lvl = ec_backlight_level(bd->props.brightness);
+	bool target_powered = !backlight_is_blank(bd);
 
 	if (lvl < 0)
 		return -EIO;
-	if (ec_set_brightness(lvl))
-		return -EIO;
 
-	return 0;
+	if (target_powered != bl_powered) {
+		ret = ec_backlight_set_power(target_powered);
+		if (ret)
+			return ret;
+
+		bl_powered = target_powered;
+	} else {
+		ret = ec_set_brightness(lvl);
+	}
+
+	return ret;
 }
 
 static int loongson_laptop_get_brightness(struct backlight_device *bd)
@@ -384,7 +408,7 @@ static const struct backlight_ops backlight_laptop_ops = {
 
 static int laptop_backlight_register(void)
 {
-	int status = 0;
+	int status = 0, ret;
 	struct backlight_properties props;
 
 	memset(&props, 0, sizeof(props));
@@ -392,44 +416,20 @@ static int laptop_backlight_register(void)
 	if (!acpi_evalf(hotkey_handle, &status, "ECLL", "d"))
 		return -EIO;
 
+	ret = ec_backlight_set_power(true);
+	if (ret)
+		return ret;
+
+	bl_powered = true;
+
 	props.brightness = ec_get_brightness();
 	props.max_brightness = status;
+	props.power = BACKLIGHT_POWER_ON;
 	props.type = BACKLIGHT_PLATFORM;
 
 	backlight_device_register("loongson_laptop",
 				NULL, NULL, &backlight_laptop_ops, &props);
 
-	return 0;
-}
-
-int loongson_laptop_turn_on_backlight(void)
-{
-	int status;
-	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
-	struct acpi_object_list args = { 1, &arg0 };
-
-	arg0.integer.value = 1;
-	status = acpi_evaluate_object(NULL, "\\BLSW", &args, NULL);
-	if (ACPI_FAILURE(status)) {
-		pr_info("Loongson lvds error: 0x%x\n", status);
-		return -ENODEV;
-	}
-
-	return 0;
-}
-
-int loongson_laptop_turn_off_backlight(void)
-{
-	int status;
-	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
-	struct acpi_object_list args = { 1, &arg0 };
-
-	arg0.integer.value = 0;
-	status = acpi_evaluate_object(NULL, "\\BLSW", &args, NULL);
-	if (ACPI_FAILURE(status)) {
-		pr_info("Loongson lvds error: 0x%x\n", status);
-		return -ENODEV;
-	}
 
 	return 0;
 }
-- 
2.49.0