Linux-ACPI Archive on lore.kernel.org
 help / color / Atom feed
From: Ricardo Ribalda <ribalda@chromium.org>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
	linux-acpi@vger.kernel.org,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-gpio@vger.kernel.org
Subject: Re: [PATCH v1 2/3] Documentation: firmware-guide: gpio-properties: active_low only for GpioIo()
Date: Wed, 28 Oct 2020 22:10:42 +0100
Message-ID: <CANiDSCtRDwfFo9HE84iujjFe6h9aS6b3B8wkz5Rt0aO8=XMsNg@mail.gmail.com> (raw)
In-Reply-To: <20201028205101.47583-2-andriy.shevchenko@linux.intel.com>

Hi Andy

Thanks for your patch and super fast response.

I think there are two different concepts here:

1) when the pin has a low value, it is  0 or a 1? =>active_low

2) when do I get an irq, low->high or high->low => irq polarity

When I read the acpi spec for GpioInt()
https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf page
934, it has the same problem as for GpioIo(), it does not express the
active_low and this is where the _DSD field comes handy.

Without using the active_low, how can we describe  a pin that is
active low and has to trigger an irq on both edges?

Thanks again


On Wed, Oct 28, 2020 at 9:51 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> It appears that people may misinterpret active_low field in _DSD
> for GpioInt() resource. Add a paragraph to clarify this.
>
> Reported-by: Ricardo Ribalda <ribalda@chromium.org>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  Documentation/firmware-guide/acpi/gpio-properties.rst | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/Documentation/firmware-guide/acpi/gpio-properties.rst b/Documentation/firmware-guide/acpi/gpio-properties.rst
> index e6e65ceb2ca1..370fe46c6af9 100644
> --- a/Documentation/firmware-guide/acpi/gpio-properties.rst
> +++ b/Documentation/firmware-guide/acpi/gpio-properties.rst
> @@ -55,6 +55,9 @@ Since ACPI GpioIo() resource does not have a field saying whether it is
>  active low or high, the "active_low" argument can be used here.  Setting
>  it to 1 marks the GPIO as active low.
>
> +Note, active_low in _DSD does not make sense for GpioInt() resource and
> +must be 0. GpioInt() resource has its own means of defining it.
> +
>  In our Bluetooth example the "reset-gpios" refers to the second GpioIo()
>  resource, second pin in that resource with the GPIO number of 31.
>
> --
> 2.28.0
>


-- 
Ricardo Ribalda

  reply index

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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CANiDSCtRDwfFo9HE84iujjFe6h9aS6b3B8wkz5Rt0aO8=XMsNg@mail.gmail.com' \
    --to=ribalda@chromium.org \
    --cc=andriy.shevchenko@linux.intel.com \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-gpio@vger.kernel.org \
    --cc=mika.westerberg@linux.intel.com \
    --cc=rjw@rjwysocki.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ACPI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-acpi/0 linux-acpi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-acpi linux-acpi/ https://lore.kernel.org/linux-acpi \
		linux-acpi@vger.kernel.org
	public-inbox-index linux-acpi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-acpi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git