Re: [PATCH v1] pinctrl: intel: Avoid potential glitches if pin is in GPIO mode

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Mon, Oct 14, 2019 at 11:51 AM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:

> When consumer requests a pin, in order to be on the safest side,
> we switch it first to GPIO mode followed by immediate transition
> to the input state. Due to posted writes it's luckily to be a single
> I/O transaction.
>
> However, if firmware or boot loader already configures the pin
> to the GPIO mode, user expects no glitches for the requested pin.
> We may check if the pin is pre-configured and leave it as is
> till the actual consumer toggles its state to avoid glitches.
>
> Fixes: 7981c0015af2 ("pinctrl: intel: Add Intel Sunrisepoint pin controller and GPIO support")
> Depends-on: f5a26acf0162 ("pinctrl: intel: Initialize GPIO properly when used through irqchip")
> Cc: fei.yang@xxxxxxxxx
> Reported-by: Oliver Barta <oliver.barta@xxxxxxxxx>
> Reported-by: Malin Jonsson <malin.jonsson@xxxxxxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

You surely know this best, should it also be tagged for stable?

Yours,
Linus Walleij