Re: [PATCH v4] backlight: gpio_backlight: Drop output GPIO direction check for initial power state

[Linus Walleij]

On Fri, Jul 21, 2023 at 11:29 AM Ying Liu <victor.liu@xxxxxxx> wrote:

> If GPIO pin is in input state but backlight is currently off due to
> default pull downs,

Oh what an interesting corner case!

> then initial power state is set to FB_BLANK_UNBLANK
> in DT boot mode with phandle link and the backlight is effectively
> turned on in gpio_backlight_probe(), which is undesirable according to
> patch description of commit ec665b756e6f ("backlight: gpio-backlight:
> Correct initial power state handling").
>
> Quote:
> ---8<---
> If in DT boot we have phandle link then leave the GPIO in a state which the
> bootloader left it and let the user of the backlight to configure it further.
> ---8<---
>
> So, let's drop output GPIO direction check and only check GPIO value to set
> the initial power state.
>
> Fixes: 706dc68102bc ("backlight: gpio: Explicitly set the direction of the GPIO")
> Signed-off-by: Liu Ying <victor.liu@xxxxxxx>

The solutions seems fine.
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij