From: Linus Walleij <linus.walleij@linaro.org>
To: Mike Looijmans <mike.looijmans@topic.nl>
Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
Dmitry Mastykin <mastichi@gmail.com>,
Evgenii Shatokhin <e.shatokhin@yadro.com>,
Arturas Moskvinas <arturas.moskvinas@gmail.com>,
Andreas Kaessens <akaessens@gmail.com>,
Radim Pavlik <radim.pavlik@tbs-biometrics.com>,
Thomas Preston <thomas.preston@codethink.co.uk>
Subject: Re: [PATCH] pinctrl-mcp23s08: Reset all pins to input at probe
Date: Tue, 15 Apr 2025 09:21:42 +0200 [thread overview]
Message-ID: <CACRpkdYLDLM603DHJvkMbDRo8pVZZfB6DT+ck4070zVAB4SCBQ@mail.gmail.com> (raw)
In-Reply-To: <20250314151803.28903-1-mike.looijmans@topic.nl>
On Fri, Mar 14, 2025 at 4:18 PM Mike Looijmans <mike.looijmans@topic.nl> wrote:
> At startup, the driver just assumes that all registers have their
> default values. But after a soft reset, the chip will just be in the
> state it was, and some pins may have been configured as outputs. Any
> modification of the output register will cause these pins to be driven
> low, which leads to unexpected/unwanted effects. To prevent this from
> happening, set the chip's IO configuration register to a known safe
> mode (all inputs) before toggling any other bits.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Patch tentatively applied for v6.16.
CC to some mcp23s08 users so they can check it out.
Yours,
Linus Walleij
prev parent reply other threads:[~2025-04-15 7:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1b153bce-a66a-45ee-a5c6-963ea6fb1c82.949ef384-8293-46b8-903f-40a477c056ae.8cb9c8b1-3ce2-4a2a-93ba-a38ee66a1643@emailsignatures365.codetwo.com>
2025-03-14 15:17 ` [PATCH] pinctrl-mcp23s08: Reset all pins to input at probe Mike Looijmans
2025-04-15 7:21 ` Linus Walleij [this message]
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