linux-kernel - Re: [PATCH 1/2] irq/irq_sim: provide irq_sim_fire

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Date:   Mon, 3 Dec 2018 11:57:26 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH 1/2] irq/irq_sim: provide irq_sim_fire_edge()

pon., 3 gru 2018 o 11:49 Uwe Kleine-König
<u.kleine-koenig@...gutronix.de> napisał(a):
>
> On Mon, Dec 03, 2018 at 11:23:38AM +0100, Bartosz Golaszewski wrote:
> > niedz., 2 gru 2018 o 23:20 Bartosz Golaszewski <brgl@...ev.pl> napisał(a):
> > >
> > > niedz., 2 gru 2018 o 22:56 Uwe Kleine-König
> > > <u.kleine-koenig@...gutronix.de> napisał(a):
> > > >
> > > > Hello,
> > > >
> > > > On Thu, Nov 29, 2018 at 07:14:45PM +0100, Bartosz Golaszewski wrote:
> > > > > We're getting too much into details of how to handle simulated
> > > > > interrupts and we can continue discussing it, but meanwhile I'd like
> > > > > to address a different thing:
> > > > >
> > > > > Thomas, Linus: after commit fa38869b0161 ("gpiolib: Don't support irq
> > > > > sharing for userspace") some libgpiod tests are failing because we can
> > > > > no longer depend on reading the value of a dummy GPIO after detecting
> > > > > an interrupt to know the edge of the interrupt. While these interrupts
> > > > > are triggered from debugfs and debugfs is not required to maintain
> > > > > compatibility, I thing having a working test suite for the GPIO
> > > > > subsystem and uAPI is worth applying these two patches and also the
> > > > > previous one[1].
> > > > >
> > > > > Can we have them applied for 4.20 or are there any objections?
> > > >
> > > > Just for the record: I objected the patch, Bartosz agrees to discuss
> > > > further and but because this is too much detail the patch should now be
> > > > applied anyhow to fix the test suite of an external project. This seems
> > > > wrong to me.
> > > >
> > >
> > > Just to look at it from a different perspective: we have a project
> > > whose tests rely on a behavior that was changed by Uwe's patch. While
> > > the patch is fine, we need to find a correct way of testing the GPIO
> > > user API. This may take a long time. In order to not break the tests
> > > of an external project in 4.20 I propose to patch the interrupt
> > > simulator (a component only used for testing) for now and to revisit
> > > it later without time pressure.
> > >
> > > Best regards,
> > > Bartosz
> >
> > In fact after re-reading this conversation I'm still not sure what
> > your objection is exactly. You're proposing a solution that may well
> > be nicely engineered but it's specific to your gpio-simulator.
> > Meanwhile I'm trying to provide a more generalized API for more
> > testing modules to use.
>
> I think you're generalizing something that won't find any user apart
> from your mockup driver. So I'd say the generalisation is wrong and the
> added code could better live in the mockup driver directly.
>

It used to live in the gpio-mockup driver and I generalized it
precisely because there was another driver - iio evgen - which was
doing basically the same thing. While I don't know if there'll be more
users (I'd guess it would be useful for testing purposes of other
subsystems) having the same functionality implemented once is better
than twice.

Bart