From: Linus Walleij <linusw@kernel.org>
To: xianwei.zhao@amlogic.com
Cc: Neil Armstrong <neil.armstrong@linaro.org>,
Kevin Hilman <khilman@baylibre.com>,
Jerome Brunet <jbrunet@baylibre.com>,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
linux-amlogic@lists.infradead.org, linux-gpio@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] pinctrl: meson: amlogic-a4: fix gpio output glitch
Date: Mon, 25 May 2026 10:34:11 +0200 [thread overview]
Message-ID: <CAD++jLkmm4BbOMZCbJD4H4xfa8nHfExczbXCyF7SapHzQwRZFg@mail.gmail.com> (raw)
In-Reply-To: <20260518-fix-set-value-glitch-v1-1-d350732dc934@amlogic.com>
On Mon, May 18, 2026 at 10:26 AM Xianwei Zhao via B4 Relay
<devnull+xianwei.zhao.amlogic.com@kernel.org> wrote:
> From: Xianwei Zhao <xianwei.zhao@amlogic.com>
>
> When the system transitions from bootloader to kernel, the GPIO is
> expected to keep driving high.
>
> However, the Linux kernel first configures the pin direction and then
> sets the output value. This may cause a brief low-level glitch on the
> GPIO line, which can be problematic for regulator control.
>
> By configuring the output value before switching the pin direction to
> output, the glitch can be avoided.
>
> This commit fixes the issue by swapping the configuration order.
>
> Fixes: 6e9be3abb78c ("pinctrl: Add driver support for Amlogic SoCs")
> Signed-off-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Is this a regression? I.e. does it cause problems on a supported
system with mainline?
Linus (the big penguin) is unhappy with too many non-critical fixes
so I wanna check this before this goes into fixes.
Yours,
Linus Walleij
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next prev parent reply other threads:[~2026-05-25 8:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-18 8:26 Xianwei Zhao via B4 Relay
2026-05-18 8:44 ` sashiko-bot
2026-05-18 14:32 ` Neil Armstrong
2026-05-25 8:34 ` Linus Walleij [this message]
2026-05-25 11:16 ` Xianwei Zhao
2026-05-26 9:54 ` Linus Walleij
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