linux-kernel - Re: [PATCH RFC/RFT 00/15] gpio: sysfs: add a per-chip export/unexport attribute pair

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Message-ID: <e3cb14a8e1a6ea1e9a050f8013730e56f79f62ec.camel@pengutronix.de>
Date: Mon, 23 Jun 2025 10:27:24 +0200
From: Jan Lübbe <jlu@...gutronix.de>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Ahmad Fatoum <a.fatoum@...gutronix.de>, Kent Gibson
 <warthog618@...il.com>,  Marek Vasut <marex@...x.de>, Geert Uytterhoeven
 <geert+renesas@...der.be>, Linus Walleij <linus.walleij@...aro.org>,
 linux-gpio@...r.kernel.org,  linux-kernel@...r.kernel.org, Bartosz
 Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH RFC/RFT 00/15] gpio: sysfs: add a per-chip
 export/unexport attribute pair

On Wed, 2025-06-18 at 17:56 +0200, Bartosz Golaszewski wrote:
> On Wed, Jun 18, 2025 at 3:38 PM Jan Lübbe <jlu@...gutronix.de> wrote:
> > 
> 
> [snip]
> 
> 
> > The contents of /sys/kernel/debug/gpio don't really fit any more:
> >  gpiochip10: GPIOs 660-663, parent: i2c/0-0024, pca9570, can sleep:
> >   gpio-660 (DUT_PWR_EN          |tacd                ) out hi
> >   gpio-661 (DUT_PWR_DISCH       |tacd                ) out lo
> >   gpio-662 (DUT_PWR_ADCRST      |reset               ) out lo
> > The header is inconsistent: it uses the 'gpiochip' prefix, but not the base as
> > the old class devices in /sys/class/gpio/. Perhaps something like this?
> >  chip10: GPIOs 0-2 (global IDs 660-663), parent: i2c/0-0024, pca9570, can sleep:
> >   gpio-0 (660) (DUT_PWR_EN          |tacd                ) out hi
> >   gpio-1 (661) (DUT_PWR_DISCH       |tacd                ) out lo
> >   gpio-2 (662) (DUT_PWR_ADCRST      |reset               ) out lo
> > If GPIO_SYSFS_LEGACY is disabled, the global IDs could be hidden.
> > 
> 
> After a second look: IMO this is unrelated to the sysfs changes. We
> definitely should change the debugfs output and rid it off the global
> numbers but it shouldn't be part of this series.

Agreed.

> Also: are you using
> this output in some way? Technically debugfs output is not stable ABI
> so we can modify it without considering existing users but wanted to
> run it by you to know if I'm going to break something for you.

We're not parsing debugfs. :) I just checked manually if it matched the new
naming and saw that it didn't.

Regards,
Jan
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