linux-kernel - [PATCH v2 1/2] platform/loongarch: laptop: Get brightness setting from EC on probe

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Message-ID: <20250605054828.15093-2-ziyao@disroot.org>
Date: Thu,  5 Jun 2025 05:48:27 +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>,
	stable@...r.kernel.org
Subject: [PATCH v2 1/2] platform/loongarch: laptop: Get brightness setting from EC on probe

Previously during probe, 1 is unconditionally taken as current
brightness value and set to props.brightness, which will be considered
as the brightness before suspend and restored to EC on resume. Since a
brightness value of 1 almost never matches EC's state on coldboot (my
laptop's EC defaults to 80), this causes surprising changes of screen
brightness on the first time of resume after coldboot.

Let's get brightness from EC and take it as the current brightness on
probe of the laptop driver to avoid the surprising behavior. Tested on
TongFang L860-T2 3A5000 laptop.

Cc: stable@...r.kernel.org
Fixes: 6246ed09111f ("LoongArch: Add ACPI-based generic laptop driver")
Signed-off-by: Yao Zi <ziyao@...root.org>
---
 drivers/platform/loongarch/loongson-laptop.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/loongarch/loongson-laptop.c b/drivers/platform/loongarch/loongson-laptop.c
index 99203584949d..828bd62e3596 100644
--- a/drivers/platform/loongarch/loongson-laptop.c
+++ b/drivers/platform/loongarch/loongson-laptop.c
@@ -392,7 +392,7 @@ static int laptop_backlight_register(void)
 	if (!acpi_evalf(hotkey_handle, &status, "ECLL", "d"))
 		return -EIO;

-	props.brightness = 1;
+	props.brightness = ec_get_brightness();
 	props.max_brightness = status;
 	props.type = BACKLIGHT_PLATFORM;

-- 
2.49.0