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

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Message-ID: <77dc0324-ce8d-4af4-9aaf-815bb9a1bd82@xen0n.name>
Date: Tue, 3 Jun 2025 13:44:20 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Huacai Chen <chenhuacai@...nel.org>, Yao Zi <ziyao@...root.org>
Cc: Jianmin Lv <lvjianmin@...ngson.cn>, linux-kernel@...r.kernel.org,
 loongarch@...ts.linux.dev, Mingcong Bai <jeffbai@...c.io>,
 Kexy Biscuit <kexybiscuit@...c.io>
Subject: Re: [PATCH 2/2] platform/loongarch: laptop: Support backlight power
 control

On 6/3/25 12:16, Huacai Chen wrote:
> On Sat, May 31, 2025 at 7:39 PM Yao Zi <ziyao@...root.org> wrote:
>>
>> 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 | 53 +++++++-------------
>>   1 file changed, 19 insertions(+), 34 deletions(-)
>>
>> [snip]
>>
>> -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;
>> -}
> I prefer to keep them, in downstream kernels there are users of them,
> I don't want to add them back if one day those users are upstream.

Then these symbols should be properly EXPORT_SYMBOL_GPL marked?

-- 
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/