Re: [RESEND PATCH] pinctrl: qcom: lpass-lpi: fix concurrent register updates

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, Oct 13, 2023 at 4:57 PM Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> wrote:


> The Qualcomm LPASS LPI pin controller driver uses one lock for guarding
> Read-Modify-Write code for slew rate registers.  However the pin
> configuration and muxing registers have exactly the same RMW code but
> are not protected.
>
> Pin controller framework does not provide locking here, thus it is
> possible to trigger simultaneous change of pin configuration registers
> resulting in non-atomic changes.
>
> Protect from concurrent access by re-using the same lock used to cover
> the slew rate register.  Using the same lock instead of adding second
> one will make more sense, once we add support for newer Qualcomm SoC,
> where slew rate is configured in the same register as pin
> configuration/muxing.
>
> Fixes: 6e261d1090d6 ("pinctrl: qcom: Add sm8250 lpass lpi pinctrl driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>
> ---
>
> Added Linus' review. Resending because no one picked up this patch.

What a mess, I applied the patch for fixes so I try to cram in a last
pull request before the merge window.

Yours,
Linus Walleij