From: Xianwei Zhao <xianwei.zhao@amlogic•com>
To: Linus Walleij <linusw@kernel•org>
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 19:16:20 +0800 [thread overview]
Message-ID: <0ea637d9-6d79-4c8f-8c45-68cfdd84c262@amlogic.com> (raw)
In-Reply-To: <CAD++jLkmm4BbOMZCbJD4H4xfa8nHfExczbXCyF7SapHzQwRZFg@mail.gmail.com>
Hi Linus,
Thanks for your review.
On 2026/5/25 16:34, Linus Walleij wrote:
> 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.
>
The issue only occurs when the critical power supply uses GPIO control.
Otherwise, it is not significant.
> Yours,
> Linus Walleij
next prev parent reply other threads:[~2026-05-25 11:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-18 8:26 [PATCH] pinctrl: meson: amlogic-a4: fix gpio output glitch Xianwei Zhao via B4 Relay
2026-05-18 14:32 ` Neil Armstrong
2026-05-25 8:34 ` Linus Walleij
2026-05-25 11:16 ` Xianwei Zhao [this message]
2026-05-26 9:54 ` Linus Walleij
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