From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Ricardo Ribalda <ribalda@google.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>
Subject: Re: [PATCH v1 2/3] Documentation: firmware-guide: gpio-properties: active_low only for GpioIo()
Date: Thu, 29 Oct 2020 19:25:48 +0200 [thread overview]
Message-ID: <CAHp75Vd+doPgSZQEOSAW4oRoAqPUdJyoivtNvbO5d1q-e280Eg@mail.gmail.com> (raw)
In-Reply-To: <CAHp75Vf-KXSC5x+07rH+wFgv_9xx_+DoMd9ZxTAqr_a5uxc7jA@mail.gmail.com>
On Thu, Oct 29, 2020 at 7:20 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Thu, Oct 29, 2020 at 7:17 PM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
> > On Thu, Oct 29, 2020 at 4:55 PM Ricardo Ribalda <ribalda@google.com> wrote:
> > > On Thu, Oct 29, 2020 at 3:45 PM Andy Shevchenko
> > > <andriy.shevchenko@linux.intel.com> wrote:
> > > > On Wed, Oct 28, 2020 at 10:10:42PM +0100, Ricardo Ribalda wrote:
> >
> > ...
> >
> > > > ActiveLevel field is described in 19.6.55 GpioInt (GPIO Interrupt Connection
> > > > Resource Descriptor Macro).
> > > >
> > > > > Without using the active_low, how can we describe a pin that is
> > > > > active low and has to trigger an irq on both edges?
> > > >
> > > > This is nonsense.
> > > > What does it mean?
> > >
> > > Let me try to explain myself again:
> > >
> > > I have a gpio pin that produces IRQs on both edges. so ActiveLevel is Both
> > >
> > > The problem is that the value of that pin is inverted: Low means 1 and
> > > high means 0.
> > >
> > > How can I describe that the pin "is inverted" without using the _DSD field?
> >
> > "Both edges" and "inverted" or "polarity low" in one sentence make no sense.
>
> To be on the constructive side, I can *imagine* so badly designed
> hardware that uses level and edge at the same time, but before I go to
> conclusions, can you share relevant (pieces of) datasheet?
The [1] is a real example of how GPIO is being used to detect changing
of current level of the signal.
Note, ACPI tables for that device have problems [2], but I guess you
may get the idea.
[1]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L138
[2]: https://elixir.bootlin.com/linux/latest/source/drivers/extcon/extcon-intel-int3496.c#L45
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-10-29 17:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 20:50 [PATCH v1 1/3] Documentation: firmware-guide: gpio-properties: Fix factual mistakes Andy Shevchenko
2020-10-28 20:51 ` [PATCH v1 2/3] Documentation: firmware-guide: gpio-properties: active_low only for GpioIo() Andy Shevchenko
2020-10-28 21:10 ` Ricardo Ribalda
2020-10-29 14:46 ` Andy Shevchenko
2020-10-29 14:54 ` Ricardo Ribalda
2020-10-29 17:17 ` Andy Shevchenko
2020-10-29 17:20 ` Andy Shevchenko
2020-10-29 17:25 ` Andy Shevchenko [this message]
2020-10-29 17:32 ` Ricardo Ribalda
2020-10-29 18:09 ` Ricardo Ribalda
2020-10-29 18:13 ` Andy Shevchenko
2020-10-29 18:58 ` Ricardo Ribalda
2020-10-29 19:11 ` Andy Shevchenko
2020-10-29 18:10 ` Andy Shevchenko
2020-10-29 8:13 ` Mika Westerberg
2020-10-28 20:51 ` [PATCH v1 3/3] Documentation: firmware-guide: gpio-properties: Clarify initial output state Andy Shevchenko
2020-10-29 8:16 ` Mika Westerberg
2020-10-29 8:13 ` [PATCH v1 1/3] Documentation: firmware-guide: gpio-properties: Fix factual mistakes Mika Westerberg
2020-10-29 11:10 ` Andy Shevchenko
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