From: Yao Zi <me@ziyao.cc>
To: liushuyu@aosc.io, linux-kernel@vger.kernel.org,
Huacai Chen <chenhuacai@kernel.org>,
Jianmin Lv <lvjianmin@loongson.cn>,
WANG Xuerui <kernel@xen0n.name>, Yao Zi <ziyao@disroot.org>
Cc: loongarch@lists.linux.dev, Mingcong Bai <jeffbai@aosc.io>,
Kexy Biscuit <kexybiscuit@aosc.io>,
stable@vger.kernel.org, Yao Zi <me@ziyao.cc>
Subject: Re: [PATCH] platform/loongarch: laptop: explicitly reset the bl_powered state when resuming
Date: Wed, 22 Jul 2026 16:39:59 +0000 [thread overview]
Message-ID: <amDyX9gPxjT4Pd1d@pie> (raw)
In-Reply-To: <20260722044457.1333404-1-liushuyu@aosc.io>
On Wed, Jul 22, 2026 at 12:44:50PM +0800, liushuyu@aosc.io wrote:
> From: Zixing Liu <liushuyu@aosc.io>
>
> On EAECIS NL60R with EC firmware version 1.11, resuming from S3 has a very
> high chance (>= 90%) of causing the EC to lose the previous backlight
> power state. When this happens, the laptop resumes normally from S3, but
> the backlight remains off (when shining on the screen with a flash light,
> we can see the screen contents are updating normally).
>
> Since there is no generic way to query the EC's backlight state on
> Loongson laptop platforms, assume the worst-case scenario and restart the
> backlight power inside the kernel each time the system resumes.
>
> Cc: stable@vger.kernel.org
> Fixes: 53c762b47f72 ("platform/loongarch: laptop: Add backlight power control support")
> Signed-off-by: Zixing Liu <liushuyu@aosc.io>
Tested on my TongFang L860-T2 3A5000 laptop, which isn't affected by
the EC issue, after resuming from S3 the brightness kept unchanged,
no regression is observed.
Tested-by: Yao Zi <me@ziyao.cc>
Regards,
Yao Zi
prev parent reply other threads:[~2026-07-22 16:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-22 4:44 [PATCH] platform/loongarch: laptop: explicitly reset the bl_powered state when resuming liushuyu
2026-07-22 12:51 ` Huacai Chen
2026-07-22 16:39 ` Yao Zi [this message]
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