From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
devicetree@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Walleij <linus.walleij@linaro.org>,
Alexandre Courbot <gnurou@gmail.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Bryan Wu <cooloney@gmail.com>, Lee Jones <lee.jones@linaro.org>,
Grant Likely <grant.likely@linaro.org>,
Aaron Lu <aaron.lu@intel.com>,
Darren Hart <dvhart@linux.intel.com>
Subject: Re: [PATCH v3 04/15] ACPI: Document ACPI device specific properties
Date: Thu, 2 Oct 2014 13:41:23 +0300 [thread overview]
Message-ID: <20141002104123.GJ1786@lahna.fi.intel.com> (raw)
In-Reply-To: <1979325.jM0BQzDCTX@wuerfel>
On Wed, Oct 01, 2014 at 09:59:14AM +0200, Arnd Bergmann wrote:
> On Wednesday 01 October 2014 04:11:20 Rafael J. Wysocki wrote:
> > From: Mika Westerberg <mika.westerberg@linux.intel.com>
> >
> > This document describes the data format and interfaces of ACPI device
> > specific properties.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Signed-off-by: Darren Hart <dvhart@linux.intel.com>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Overall looks sane, but I wonder if we should try harder to not duplicate
> some of the mistakes we made in the DT bindings. Two points in particular
> stick out:
>
> > +2.3 Strings
> > +-----------
> > +String properties can be used to describe many things like labels for GPIO
> > +buttons, compability ids, etc.
> > +
> > +A string property looks like this:
> > +
> > + Package () {"pwm-names", "backlight"},
>
> The way we name things in DT using separate "foos" and "foo-names" properties
> is a bit quirky. Those are always defined on a per-subsystem level, not
> a per-device level though, so it should be possible to come up with a
> better representation in ACPI.
>
> Since the device driver should never look into the "foo-names" property
> itself but just pass down the name into the subsystem, the "foo" subsystem
> could instead have a way to add an (optional) name for each reference.
>
> This is something the DT syntax doesn't allow because you can't have
> both a phandle and a string in a single property but I think the ACPI
> packages can do it, and it wouldn't change the basic structure.
ACPI packages can hold anything (even other packages) but one goal with
the _DSD implementation was to reuse existing DT bindings wherever it
makes sense even if they would not always be optimal for ACPI. So the
current acpi_dev_get_property_reference() is modelled after
corresponding DT function and it allows only integer arguments to
accompany the reference.
Doing that allows taking the existing DT description, package it inside
ACPI _DSD and be done with it.
> > +The referenced ACPI device is returned in args->adev if found.
> > +
> > +In addition to simple object references it is also possible to have object
> > +references with arguments. These are represented in ASL as follows:
> > +
> > + Device (\_SB.PCI0.PWM)
> > + {
> > + Name (_DSD, Package () {
> > + ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> > + Package () {
> > + Package () {"#pwm-cells", 2}
> > + }
> > + })
> > + }
> > +
>
> Similarly, the "#foo-cells" syntax is an artifact of the limitations of the
> DT syntax, and I'd assume there would be a better way to encode this
> in ACPI. Also, a "cell" in Open Firmware is defined as a big-endian
> 32-bit value, which doesn't directly correspond to something in ACPI,
> and the '#' character is an artifact of the use of the Forth language
> in Open Firmware, which you also don't have here.
Same here, we tried to make it follow closely the DT description. It is
probably not the best/optimal encoding for ACPI but it is documented
well in Documentation/devicetree/bindings so why not use it.
The summary email from Darren at KS also mentions that for the existing
drivers, the existing schemas should be common for both implementations [1].
For new bindings we probably should look out if they can be better
represented using ACPI types.
[1] http://lwn.net/Articles/609373/
next prev parent reply other threads:[~2014-10-02 10:41 UTC|newest]
Thread overview: 130+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-16 11:52 [RFC PATCH v2 00/16] Add ACPI _DSD and unified device properties support Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 01/16] ACPI: Add support for device specific properties Mika Westerberg
2014-10-06 13:50 ` Grant Likely
2014-10-06 14:32 ` Mika Westerberg
2014-10-06 16:25 ` Darren Hart
2014-09-16 11:52 ` [RFC PATCH v2 02/16] Driver core: Unified device properties interface for platform firmware Mika Westerberg
2014-09-17 18:28 ` Greg Kroah-Hartman
2014-09-16 11:52 ` [RFC PATCH v2 03/16] ACPI: Allow drivers to match using Device Tree compatible property Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 04/16] ACPI: Document ACPI device specific properties Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 05/16] mfd: Add ACPI support Mika Westerberg
2014-09-16 21:54 ` Lee Jones
2014-09-24 12:00 ` Lee Jones
2014-09-16 11:52 ` [RFC PATCH v2 06/16] gpio / ACPI: Add support for _DSD device properties Mika Westerberg
2014-09-23 15:27 ` Linus Walleij
2014-09-16 11:52 ` [RFC PATCH v2 07/16] gpio: Add support for unified device properties interface Mika Westerberg
2014-09-23 15:25 ` Linus Walleij
2014-09-23 15:45 ` Arnd Bergmann
2014-09-23 15:52 ` Mika Westerberg
2014-09-23 16:17 ` Dmitry Torokhov
2014-09-23 20:31 ` Rafael J. Wysocki
2014-09-23 16:25 ` Rafael J. Wysocki
2014-09-23 16:26 ` Arnd Bergmann
2014-09-23 20:47 ` Rafael J. Wysocki
2014-09-24 7:55 ` Arnd Bergmann
2014-09-24 14:08 ` Rafael J. Wysocki
2014-09-23 21:15 ` Darren Hart
2014-09-24 9:12 ` Arnd Bergmann
2014-09-24 9:38 ` Mika Westerberg
2014-09-24 14:11 ` Rafael J. Wysocki
2014-09-26 3:21 ` Darren Hart
2014-09-26 8:36 ` Arnd Bergmann
2014-09-26 14:42 ` Rafael J. Wysocki
2014-10-07 13:37 ` Linus Walleij
2014-10-07 15:37 ` Andy Shevchenko
2014-10-07 23:57 ` Rafael J. Wysocki
2014-09-16 11:52 ` [RFC PATCH v2 08/16] gpio: sch: Consolidate core and resume banks Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 09/16] leds: leds-gpio: Add support for GPIO descriptors Mika Westerberg
2014-09-19 8:18 ` Alexandre Courbot
2014-09-24 7:55 ` Linus Walleij
2014-09-24 9:42 ` Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 10/16] leds: leds-gpio: Make use of device property API Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 11/16] leds: leds-gpio: Add ACPI probing support Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 12/16] input: gpio_keys_polled - Add support for GPIO descriptors Mika Westerberg
2014-09-19 8:22 ` Alexandre Courbot
2014-09-24 8:02 ` Linus Walleij
2014-09-16 11:52 ` [RFC PATCH v2 13/16] input: gpio_keys_polled - Make use of device property API Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 14/16] input: gpio_keys_polled - Add ACPI probing support Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 15/16] misc: at25: Make use of device property API Mika Westerberg
2014-09-16 11:52 ` [RFC PATCH v2 16/16] misc: at25: Add ACPI probing support Mika Westerberg
2014-09-21 0:26 ` [RFC PATCH v2 00/16] Add ACPI _DSD and unified device properties support Rafael J. Wysocki
2014-09-24 8:34 ` Lee Jones
2014-09-24 9:45 ` Mika Westerberg
2014-09-22 23:29 ` Bryan Wu
2014-10-01 2:08 ` [PATCH v3 00/15] " Rafael J. Wysocki
2014-10-01 2:08 ` [PATCH v3 01/15] ACPI: Add support for device specific properties Rafael J. Wysocki
2014-10-01 7:38 ` Arnd Bergmann
2014-10-01 2:10 ` [PATCH v3 02/15] Driver core: Unified device properties interface for platform firmware Rafael J. Wysocki
2014-10-01 7:47 ` Arnd Bergmann
2014-10-01 22:09 ` Rafael J. Wysocki
2014-10-01 23:01 ` Rafael J. Wysocki
2014-10-02 7:46 ` Arnd Bergmann
2014-10-02 16:50 ` Rafael J. Wysocki
2014-10-02 0:03 ` Greg Kroah-Hartman
2014-10-01 2:10 ` [PATCH v3 03/15] ACPI: Allow drivers to match using Device Tree compatible property Rafael J. Wysocki
2014-10-01 7:48 ` Arnd Bergmann
2014-10-03 13:43 ` Mark Rutland
2014-10-03 17:59 ` Dmitry Torokhov
2014-10-04 0:02 ` Rafael J. Wysocki
2014-10-01 2:11 ` [PATCH v3 04/15] ACPI: Document ACPI device specific properties Rafael J. Wysocki
2014-10-01 7:59 ` Arnd Bergmann
2014-10-02 10:41 ` Mika Westerberg [this message]
2014-10-02 11:51 ` Arnd Bergmann
2014-10-02 12:15 ` Mika Westerberg
2014-10-02 12:46 ` Arnd Bergmann
2014-10-02 13:36 ` Mika Westerberg
2014-10-02 14:29 ` Arnd Bergmann
2014-10-02 14:38 ` Mika Westerberg
2014-10-02 14:55 ` Arnd Bergmann
2014-10-03 13:56 ` Mark Rutland
2014-10-03 15:02 ` Arnd Bergmann
2014-10-03 23:58 ` Rafael J. Wysocki
2014-10-04 10:56 ` Arnd Bergmann
2014-10-05 21:40 ` Rafael J. Wysocki
2014-10-03 2:03 ` Rafael J. Wysocki
2014-10-03 8:12 ` Mika Westerberg
2014-10-03 13:58 ` Mark Rutland
2014-10-03 14:38 ` Rafael J. Wysocki
2014-10-03 14:35 ` Mark Rutland
2014-10-04 0:13 ` Rafael J. Wysocki
2014-10-04 10:59 ` Arnd Bergmann
2014-10-05 22:26 ` Rafael J. Wysocki
2014-10-03 13:48 ` Mark Rutland
2014-10-04 0:16 ` Rafael J. Wysocki
2014-10-01 2:12 ` [PATCH v3 05/15] gpio / ACPI: Add support for _DSD device properties Rafael J. Wysocki
2014-10-01 8:03 ` Arnd Bergmann
2014-10-05 10:36 ` Alexandre Courbot
2014-10-05 21:20 ` Rafael J. Wysocki
2014-10-01 2:14 ` [PATCH v3 06/15] gpio: Support for unified device properties interface Rafael J. Wysocki
2014-10-01 2:15 ` [PATCH v3 07/15] gpio: sch: Consolidate core and resume banks Rafael J. Wysocki
2014-10-01 2:15 ` [PATCH v3 08/15] leds: leds-gpio: Add support for GPIO descriptors Rafael J. Wysocki
2014-10-01 8:05 ` Arnd Bergmann
2014-10-01 2:16 ` [PATCH v3 09/15] leds: leds-gpio: Make use of device property API Rafael J. Wysocki
2014-10-03 14:07 ` Mark Rutland
2014-10-04 0:18 ` Rafael J. Wysocki
2014-10-01 2:17 ` [PATCH v3 10/15] leds: leds-gpio: Add ACPI probing support Rafael J. Wysocki
2014-10-01 8:13 ` Arnd Bergmann
2014-10-01 9:13 ` Mika Westerberg
2014-10-01 10:01 ` Arnd Bergmann
2014-10-01 11:59 ` Mika Westerberg
2014-10-01 13:52 ` Arnd Bergmann
2014-10-01 14:04 ` Mika Westerberg
2014-10-01 14:14 ` Arnd Bergmann
2014-10-02 9:55 ` Mika Westerberg
2014-10-02 10:44 ` Arnd Bergmann
2014-10-01 16:30 ` Dmitry Torokhov
2014-10-01 18:11 ` Darren Hart
2014-10-01 18:21 ` Dmitry Torokhov
2014-10-01 18:22 ` Arnd Bergmann
2014-10-01 2:17 ` [PATCH v3 11/15] input: gpio_keys_polled - Add support for GPIO descriptors Rafael J. Wysocki
2014-10-01 8:13 ` Arnd Bergmann
2014-10-01 2:20 ` [PATCH v3 12/15] input: gpio_keys_polled - Make use of device property API Rafael J. Wysocki
2014-10-01 2:20 ` [PATCH v3 13/15] input: gpio_keys_polled - Add ACPI probing support Rafael J. Wysocki
2014-10-01 7:48 ` Dmitry Torokhov
2014-10-01 9:15 ` Mika Westerberg
2014-10-01 16:28 ` Dmitry Torokhov
2014-10-02 9:53 ` Mika Westerberg
2014-10-01 2:21 ` [PATCH v3 14/15] misc: at25: Make use of device property API Rafael J. Wysocki
2014-10-01 8:14 ` Arnd Bergmann
2014-10-01 2:22 ` [PATCH v3 15/15] misc: at25: Add ACPI probing support Rafael J. Wysocki
2014-10-01 8:15 ` Arnd Bergmann
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