linux-kernel - Re: [PATCH v2 0/9] gpio: mockup: improve the user-space testing interface

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Message-ID: <20190211223313.34f6c8be@why.wild-wind.fr.eu.org>
Date:   Mon, 11 Feb 2019 22:33:13 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH v2 0/9] gpio: mockup: improve the user-space testing
 interface

On Wed, 6 Feb 2019 11:23:46 +0100
Bartosz Golaszewski <brgl@...ev.pl> wrote:

> wt., 29 sty 2019 o 09:44 Bartosz Golaszewski <brgl@...ev.pl> napisał(a):
> >
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > This series aims at reworking the gpio-mockup debugfs interface. The
> > reason for that is the fact that certain known problems with this
> > testing module exist and the user-space tests are broken anyway
> > after commit fa38869b0161 ("gpiolib: Don't support irq sharing
> > for userspace") which made it impossible for gpio-mockup to ignore
> > certain events (e.g. only receive notifications about rising edge
> > events).
> >
> > The first three patches improve the interrupt simulator. The first one
> > makes the struct irq_chip part of the irq_sim structure so that we can
> > support multiple instances at once. The second delegates the irq number
> > mapping to the irq domain subsystem. The third patch provides a helper
> > that will allow users to specify the type of the fired interrupt so that
> > the configuration set by the set_type() callback can be taken into account.
> >
> > Next six patches improve the gpio-mockup module. Patches 4-5 have been
> > reviewed before but missed the last merge window. Patch 6 is there
> > because we're already breaking the debugfs interface anyway and it
> > removes a link that has no users. Patches 7-8 are minor tweaks.
> >
> > Last patch introduces a rework of the debugfs interface. With this
> > change each mockup chip is represented by a directory named after the
> > chip's device name under <debugfs mount point>/gpio-mockup/. Each line
> > is represented by a file using the line's offset as the name under the
> > chip's directory. Reading from the line's file yields the current
> > *value*, writing to the line's file changes the current "pull". Default
> > pull for mockup lines is down. More info on that can be found in the
> > comment added by this change to the gpio-mockup code.
> >
> > This is somewhat inspired by the idea of the gpio-simulator by
> > Uwe Kleine-König except that I strongly belive that when testing
> > certain user API code paths we should not be using the same paths for
> > verification. That's why there's a separate interface (debugfs) sharing
> > as little as possible with the character device that allows to check if
> > various operations (reading and setting values, events) work as
> > expected instead of two connected dummy chips sharing the same
> > interface.
> >
> > If accepted this will of course require major modification of user-space
> > tests in libgpiod once upstream.
> >
> > v1 -> v2:
> > - instead of providing the irq_sim_get_type() helper, move the irq type
> >   logic into the simulator and provide a helper that allows users to specify
> >   the type of the fired interrupt
> >
> > Bartosz Golaszewski (9):
> >   irq/irq_sim: don't share the irq_chip structure between simulators
> >   irq/irq_sim: use irq domain
> >   irq/irq_sim: provide irq_sim_fire_type()
> >   gpio: mockup: add locking
> >   gpio: mockup: implement get_multiple()
> >   gpio: mockup: don't create the debugfs link named after the label
> >   gpio: mockup: change the type of 'offset' to unsigned int
> >   gpio: mockup: change the signature of unlocked get/set helpers
> >   gpio: mockup: rework debugfs interface
> >
> >  drivers/gpio/gpio-mockup.c | 185 +++++++++++++++++++++++++++++++------
> >  include/linux/irq_sim.h    |  17 +++-
> >  kernel/irq/irq_sim.c       | 126 ++++++++++++++++++-------
> >  3 files changed, 263 insertions(+), 65 deletions(-)
> >
> > --
> > 2.19.1
> >  
> 
> Marc, Thomas,
> 
> if there are no objections - could you please ack the three first
> patches and let me take them through the GPIO tree? I would really
> appreciate if we could have them in v5.1.

There are certainly a number of questions that have to be answered
before this can be merged. I can't find a rational for patch #1, and
patch #2 looks like a set of misuse of APIs.

At the very least, I'd like to see these questions answered, and the
code in patch #2 fixed.

Thanks,

	M.
-- 
Without deviation from the norm, progress is not possible.