Re: [PATCH v4] wifi: ath9k: Obtain system GPIOS from descriptors

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, Mar 16, 2026 at 05:09:22AM -0400, Bartosz Golaszewski wrote:
> On Fri, 13 Mar 2026 22:53:43 +0100, Linus Walleij <linusw@kernel.org> said:
> > The ath9k has an odd use of system-wide GPIOs: if the chip
> > does not have internal GPIO capability, it will try to obtain a
> > GPIO line from the system GPIO controller:
> >
> >   if (BIT(gpio) & ah->caps.gpio_mask)
> >         ath9k_hw_gpio_cfg_wmac(...);
> >   else if (AR_SREV_SOC(ah))
> >         ath9k_hw_gpio_cfg_soc(ah, gpio, out, label);
> >
> > Where ath9k_hw_gpio_cfg_soc() will attempt to issue
> > gpio_request_one() passing the local GPIO number of the controller
> > (0..31) to gpio_request_one().
> >
> > This is somewhat peculiar and possibly even dangerous: there is
> > nowadays no guarantee of the numbering of these system-wide
> > GPIOs, and assuming that GPIO 0..31 as used by ath9k would
> > correspond to GPIOs 0..31 on the system as a whole seems a bit
> > wild.
> >
> > Register all 32 GPIOs at index 0..31 directly in the ATH79K
> > GPIO driver and associate with the NULL device (making them
> > widely available) if and only if we are probing ATH79K wifi
> > from the AHB bus (used for SoCs). We obtain these offsets from
> > the NULL device if necessary.
> >
> > These GPIOs should ideally be defined in the device tree
> > instead, but we have no control over that for the legacy
> > code path.
> >
> > Testcompiled with the ath79 defconfig.
> >
> > Reported-by: Michał Kępień <kernel@kempniu.pl>
> > Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Signed-off-by: Linus Walleij <linusw@kernel.org>
> > ---
> > This patch set is a long standing attempt to get rid of the global
> > GPIO numbers from the ath9k Wireless driver.
> >
> > Maybe Kalle can merge this to the Wireless tree if we agree on this
> > hack solution.
> >
> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> > ---
> > Changes in v4:
> > - Fix review comments from Andy.
> > - Collect ACKs.
> 
> I think this did not work. :)

It's just extra SoB where it's not needed, but the tags are collected in
the proper commit message.

-- 
With Best Regards,
Andy Shevchenko