From: Linus Walleij <linusw@kernel.org>
To: Chen-Yu Tsai <wenst@chromium.org>
Cc: Sean Wang <sean.wang@kernel.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
linux-mediatek@lists.infradead.org, linux-gpio@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] pinctrl: mediatek: paris: bypass pinctrl GPIO layer in set GPIO direction
Date: Mon, 11 May 2026 22:00:46 +0200 [thread overview]
Message-ID: <CAD++jLnpsmV=yqjrFZiqqRxHVM-7pG3SZ15DKakj_3ODnP4wkg@mail.gmail.com> (raw)
In-Reply-To: <20260505104003.1811841-1-wenst@chromium.org>
On Tue, May 5, 2026 at 12:40 PM Chen-Yu Tsai <wenst@chromium.org> wrote:
> pinctrl_gpio_direction_input() / pinctrl_gpio_direction_output() take
> the pinctrl mutex. This causes a gpiochip operations to need to sleep.
> Worse yet, the .can_sleep field in the gpiochip is not set. This causes
> the shared GPIO proxy to trip over, as it uses gpiod_cansleep() to check
> whether it can use a spinlock or needs a mutex. In this case, it ends
> up taking a spinlock, then calls pinctrl_gpio_direction_output(), which
> takes a mutex. This causes a huge warning.
>
> While this class of Mediatek hardware does not have separate clear/set
> registers, the pinctrl context has a spinlock that is taken whenever
> a register read-modify-write is done. Also, once the GPIO function is
> selected / muxed in, further GPIO operations do not involve pinctrl
> operations or state. The GPIO direction and level values do not require
> toggling the pinmux or any other pin config options.
>
> Switch to directly calling mtk_pinmux_gpio_set_direction() in the GPIO
> set direction callbacks to avoid taking the pinctrl mutex. Drop the
> .gpio_set_direction field in mtk_pmxops to signal we are no longer using
> the pinctrl GPIO layer for setting the direction.
>
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Patch applied, thanks for your perseverance Chen-Yu!
Yours,
Linus Walleij
prev parent reply other threads:[~2026-05-11 20:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-05 10:39 [PATCH v2] pinctrl: mediatek: paris: bypass pinctrl GPIO layer in set GPIO direction Chen-Yu Tsai
2026-05-11 20:00 ` Linus Walleij [this message]
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