linux-kernel - Re: [PATCH v4 2/2] gpio: sch: Hook into ACPI SCI handler to catch GPIO edge events

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Date:   Wed, 17 Mar 2021 11:52:26 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Jan Kiszka <jan.kiszka@...mens.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andy Shevchenko <andy@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v4 2/2] gpio: sch: Hook into ACPI SCI handler to catch
 GPIO edge events

On Wed, Mar 17, 2021 at 07:57:44AM +0100, Jan Kiszka wrote:
> On 16.03.21 21:49, Andy Shevchenko wrote:
> > On Tue, Mar 16, 2021 at 06:26:13PM +0200, Andy Shevchenko wrote:
> >> From: Jan Kiszka <jan.kiszka@...mens.com>
> >>
> >> Neither the ACPI description on the Quark platform provides the required
> >> information is to do establish generic handling nor hardware capable of
> >> doing it. According to the datasheet the hardware can generate SCI events.
> >> Therefore, we need to hook from the driver directly into SCI handler of
> >> the ACPI subsystem in order to catch and report GPIO-related events.
> >>
> >> Validated on the Quark-based IOT2000 platform.
> > 
> > This patch must be dropped completely. SCI handler is not correct way to do
> > this. The proper way (and we have already few examples in the kernel) is to
> > register GPE event.
> 
> As explained above, this is not supported by the preexisting firmware,
> and there won't be any updates to it anymore.
> 
> This platform is history, the SoC was discontinued by Intel long ago,
> and our devices reaching their support end as well. The race to upstream
> was lost in this case - backlog too long, we being too slow.

So you have no device to test and there is actually no device which has this
capability in the wild.

Am I reading this correct?

In any case, we have platforms in the wild that actually support GPEs and this
makes sense for them.

> > It took me a while to gather all bits of this puzzle.
> > 
> > At least now I get an event, but kernel oopses, I'll continue debugging
> > tomorrow.

-- 
With Best Regards,
Andy Shevchenko