Re: [PATCH 0/8] gpio: implement the configfs testing module - Uwe Kleine-König

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Joel Becker <jlbec@evilplan.org>, Christoph Hellwig <hch@lst.de>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Kent Gibson <warthog618@gmail.com>,
	linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: [PATCH 0/8] gpio: implement the configfs testing module
Date: Sat, 30 Jan 2021 22:20:09 +0100	[thread overview]
Message-ID: <20210130212009.2uugdj6vmisegau2@pengutronix.de> (raw)
In-Reply-To: <20210129134624.9247-1-brgl@bgdev.pl>

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Hello,

On Fri, Jan 29, 2021 at 02:46:16PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> This series adds a new GPIO testing module based on configfs committable items
> and sysfs. The goal is to provide a testing driver that will be configurable
> at runtime (won't need module reload) and easily extensible. The control over
> the attributes is also much more fine-grained than in gpio-mockup.
> 
> I am aware that Uwe submitted a virtual driver called gpio-simulator some time
> ago and I was against merging it as it wasn't much different from gpio-mockup.
> I would ideally want to have a single testing driver to maintain so I am
> proposing this module as a replacement for gpio-mockup but since selftests
> and libgpiod depend on it and it also has users in the community, we can't
> outright remove it until everyone switched to the new interface. As for Uwe's
> idea for linking two simulated chips so that one controls the other - while
> I prefer to have an independent code path for controlling the lines (hence
> the sysfs attributes), I'm open to implementing it in this new driver. It
> should be much more feature friendly thanks to configfs than gpio-mockup.

Funny you still think about my simulator driver. I recently thought
about reanimating it for my private use. The idea was to implement a
rotary-encoder driver (that contrast to
drivers/input/misc/rotary_encoder.c really implements an encoder and not
a decoder). With the two linked chips I can plug
drivers/input/misc/rotary_encoder.c on one side and my encoder on the
other to test both drivers completely in software.

I didn't look into your driver yet, but getting such a driver into
mainline would be very welcome!

I intend to look into your driver next week, but please don't hold back
on merging for my feedback.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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