From: "Michał Kępień" <kernel@kempniu.pl>
To: Linus Walleij <linusw@kernel.org>
Cc: "Jeff Johnson" <jeff.johnson@oss.qualcomm.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Arnd Bergmann" <arnd@arndb.de>, "Alban Bedel" <albeu@free.fr>,
"Bartosz Golaszewski" <brgl@bgdev.pl>,
"Toke Høiland-Jørgensen" <toke@toke.dk>,
linux-wireless@vger.kernel.org,
brcm80211-dev-list.pdl@broadcom.com, linux-gpio@vger.kernel.org,
"Bartosz Golaszewski" <bartosz.golaszewski@oss.qualcomm.com>
Subject: Re: [PATCH v6] wifi: ath9k: Obtain system GPIOS from descriptors
Date: Tue, 7 Apr 2026 17:13:16 +0200 [thread overview]
Message-ID: <adUfDB4y-xt5QorX@larwa.hq.kempniu.pl> (raw)
In-Reply-To: <20260317-descriptors-wireless-v6-1-b19ecff9cd2b@kernel.org>
Linus,
> 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.
I could only test a 6.12 backport of v6 on real hardware as that is the
kernel version that OpenWRT's current main branch uses for my router.
That being said, the only conflict I had to resolve was the one caused
by commit 551a097118391018ddc4079cbcec6fe4e7d64bc5 ("gpio: ath79: use
new generic GPIO chip API") in ath79_gpio_probe(), i.e. no functional
changes were necessary.
After replacing the "tweaked" version of v2 with a 6.12 backport of v6
in OpenWRT's source tree, the WiFi LED still works fine on my router.
For the above:
Tested-by: Michał Kępień <kernel@kempniu.pl>
--
Best regards,
Michał Kępień
next prev parent reply other threads:[~2026-04-07 15:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-17 8:45 [PATCH v6] wifi: ath9k: Obtain system GPIOS from descriptors Linus Walleij
2026-04-07 15:13 ` Michał Kępień [this message]
2026-04-22 13:59 ` Jeff Johnson
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