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] pinctrl: mediatek: common-v1: Directly modify registers to set GPIO direction
Date: Tue, 28 Apr 2026 12:48:44 +0200 [thread overview]
Message-ID: <CAD++jLkjDozkjL-136ut4OsX5PoCe4aKrfXVyq0jtEOc4LX1dw@mail.gmail.com> (raw)
In-Reply-To: <20260427061720.2393355-1-wenst@chromium.org>
On Mon, Apr 27, 2026 at 8:17 AM 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.
>
> Since the Mediatek hardware has separate clear/set registers, there is
> no risk of clobbering other bits like with a read-modify-write pattern.
> Switch to directly setting the GPIO direction register bits to avoid
> the mutex.
>
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Here you need to at least delete the assignment of mtk_pmx_gpio_set_direction()
from:
static const struct pinmux_ops mtk_pmx_ops = {
.get_functions_count = mtk_pmx_get_funcs_cnt,
.get_function_name = mtk_pmx_get_func_name,
.get_function_groups = mtk_pmx_get_func_groups,
.set_mux = mtk_pmx_set_mux,
.gpio_set_direction = mtk_pmx_gpio_set_direction,
^ Here, it should no longer be used, right?
Yours,
Linus Walleij
prev parent reply other threads:[~2026-04-28 10:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 6:17 [PATCH] pinctrl: mediatek: common-v1: Directly modify registers to set GPIO direction Chen-Yu Tsai
2026-04-28 10:48 ` Linus Walleij [this message]
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