Re: [PATCH] platform/loongarch: laptop: explicitly reset the bl_powered state when resuming

[Yao Zi]

On Wed, Jul 22, 2026 at 12:44:50PM +0800, liushuyu@xxxxxxx wrote:
> From: Zixing Liu <liushuyu@xxxxxxx>
> 
> 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@xxxxxxxxxxxxxxx
> Fixes: 53c762b47f72 ("platform/loongarch: laptop: Add backlight power control support")
> Signed-off-by: Zixing Liu <liushuyu@xxxxxxx>

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@xxxxxxxx>

Regards,
Yao Zi