linux-kernel - Re: [PATCH 2/2] gpio: sch: Add interrupt support

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Message-ID: <5a28f22c-22f7-760a-d076-68ff19800d44@siemens.com>
Date:   Wed, 24 Apr 2019 10:25:40 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 2/2] gpio: sch: Add interrupt support

On 24.04.19 10:18, Mika Westerberg wrote:
> On Wed, Apr 24, 2019 at 10:12:42AM +0200, Jan Kiszka wrote:
>> On 24.04.19 09:58, Mika Westerberg wrote:
>>> +Rafael and linux-acpi.
>>>
>>> On Thu, Apr 18, 2019 at 11:23:49AM +0200, Jan Kiszka wrote:
>>>> From: Jan Kiszka <jan.kiszka@...mens.com>
>>>>
>>>> Validated on the Quark platform, this adds interrupt support on rising
>>>> and/or falling edges.
>>>
>>> The irqchip parts look good to me but but the ACPI SCI handling seems
>>> weird. This is typically handled by ACPI core based on the values read
>>> from FADT ACPI table. What does it contain on this Quark platform?
>>
>> There is no FADT on the original Quark firmware, nor did we add one. As we
>> are talking about existing devices, possibly not only Quarks, I was going
>> down the ACPI-independent way to hook into the interrupt. But I'm open to
>> learn about better alternatives.
> 
> Hmm, if it does not have FADT table why would you need SCI then? Is this
> implementing some real use case?
> 

Maybe I'm looking at the wrong place: Where would I find it? There is definitely 
no separate entry under /sys/firmware/acpi/tables - but that's also true for my 
workstation.

In any case: The hardware defines that the GPIO events are sent via SCIs. That 
fact is probably not expressed in ACPI language.

Jan

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