From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Arturas Moskvinas <arturas.moskvinas@gmail.com>
Cc: linus.walleij@linaro.org, brgl@bgdev.pl,
u.kleine-koenig@pengutronix.de, linux-gpio@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] gpio: 74x164: Enable output pins after registers are reset
Date: Thu, 29 Feb 2024 12:45:46 +0200 [thread overview]
Message-ID: <ZeBgWnt8bleYVXJl@smile.fi.intel.com> (raw)
In-Reply-To: <20240229084555.43701-2-arturas.moskvinas@gmail.com>
On Thu, Feb 29, 2024 at 10:45:56AM +0200, Arturas Moskvinas wrote:
> Chip outputs are enabled[1] before actual reset is performed[2] which might
> cause pin output value to flip flop if previous pin value was set to 1 in chip.
> Change fixes that behavior by making sure chip is fully reset before all outputs
> are enabled.
>
> Flip-flop can be noticed when module is removed and inserted again and one of
> the pins was changed to 1 before removal. 100 microsecond flipping is
> noticeable on oscilloscope (100khz SPI bus).
>
> For a properly reset chip - output is enabled around 100 microseconds (on 100khz
> SPI bus) later during probing process hence should be irrelevant behavioral
> change.
> [1] - https://elixir.bootlin.com/linux/v6.7.4/source/drivers/gpio/gpio-74x164.c#L130
> [2] - https://elixir.bootlin.com/linux/v6.7.4/source/drivers/gpio/gpio-74x164.c#L150
Please, convert these to be Link tags, so
at the end it will look like
Fixes:
Link: URL1 [1]
Link: URL2 [2]
Signed-off-by:
--
With Best Regards,
Andy Shevchenko
prev parent reply other threads:[~2024-02-29 10:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-29 8:45 [PATCH v2] gpio: 74x164: Enable output pins after registers are reset Arturas Moskvinas
2024-02-29 8:54 ` Bartosz Golaszewski
2024-02-29 12:23 ` Arturas Moskvinas
2024-02-29 13:25 ` Bartosz Golaszewski
[not found] ` <f9e90eb2-60e5-4ae8-9f3f-92922294e981@gmail.com>
2024-02-29 17:39 ` Bartosz Golaszewski
2024-02-29 18:25 ` Andy Shevchenko
2024-02-29 10:45 ` Andy Shevchenko [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZeBgWnt8bleYVXJl@smile.fi.intel.com \
--to=andriy.shevchenko@linux.intel.com \
--cc=arturas.moskvinas@gmail.com \
--cc=brgl@bgdev.pl \
--cc=linus.walleij@linaro.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=u.kleine-koenig@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.