Re: [PATCH 0/8] gpio: implement the configfs testing module

Hello,

On Fri, Jan 29, 2021 at 02:46:16PM +0100, Bartosz Golaszewski wrote:

From: Bartosz Golaszewski <redacted>

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            |
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