From: Flavio Suligoi <f.suligoi@asem.it>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: How to use an ACPI declared GPIO in a userspace ...
Date: Wed, 30 Sep 2020 12:04:43 +0000 [thread overview]
Message-ID: <22753b53cd7d4dfba4ef3610f71cc462@asem.it> (raw)
In-Reply-To: <CAHp75Vdd2QjvJvLGHa1x=RaSknEG+O+YB4eJA6+2htnZ=Gf52g@mail.gmail.com>
Hi Andy,
> > > > > I was wondering if there is a generic GPIO driver that I can use
> Maybe I was not so clear, but as Bart mentioned the least you can do
> is simply define line name via "gpio-line-names" property. The problem
> here is when and how you would like to have them incorporated.
I already tried adding the "gpio-line-names" property, but the problem
is the same: no driver asks for this GPIO, as shown by the following
kernel messages:
ACPI: Host-directed Dynamic ACPI Table Load:
ACPI: SSDT 0xFFFF994034D42A00 0000E8 (v05 ASEMsp GPIO_BTN 00000001 INTL 20200717)
ACPI: \_SB_.GPO1.BTNS: PRP0001 requires 'compatible' property
So I'll start to write a simple device driver to use this GPIO.
I'll keep you informed!
> When: if ACPI tables are being provided by firmware which you may not
> alter, then you must use initramfs type of solution (no configfs,
> don't know about EFI var though). How: In that case you might have a
> chance to incorporate _DSD() method into *existing* _CRS() one.
> Possible impediments: if ACPI table from firmware already has a _DSD()
> defined or above is not working for some reason. In such a case you
> must upgrade entire DSDT via initramfs.
>
> > > > Adding Andy who knows ACPI GPIO well.
> > >
> > > Thanks.
> > >
> > > > In general, the "gpio-line-names" property is used for that and it's
> > > > supported both for device tree as well as ACPI, although I have only
> > > > ever used the former.
> > >
> > > Right. ACPI supports properties via _DSD() method.
>
> --
> With Best Regards,
> Andy Shevchenko
Thanks Andy and Bartosz for your support!
Best regards,
Flavio
next prev parent reply other threads:[~2020-09-30 12:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 15:37 How to use an ACPI declared GPIO in a userspace Flavio Suligoi
2020-09-29 15:47 ` Bartosz Golaszewski
2020-09-29 16:10 ` Andy Shevchenko
2020-09-29 16:21 ` Flavio Suligoi
2020-09-29 16:27 ` Andy Shevchenko
2020-09-30 12:04 ` Flavio Suligoi [this message]
2020-09-30 13:01 ` Andy Shevchenko
2020-09-30 15:39 ` Flavio Suligoi
2020-09-30 15:54 ` Andy Shevchenko
2020-09-30 16:10 ` Andy Shevchenko
2020-10-02 10:02 ` Flavio Suligoi
2020-10-02 12:48 ` Andy Shevchenko
2020-10-02 13:23 ` Andy Shevchenko
2020-10-02 13:29 ` Flavio Suligoi
2020-10-02 10:26 ` Flavio Suligoi
2020-10-02 12:40 ` Andy Shevchenko
2020-09-29 16:10 ` Flavio Suligoi
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