Antwort: Re: [PATCH v3 13/29] dts: Add a binding for hid-over-i2c

Wolfgang Wallner wolfgang.wallner at
Wed Apr 8 21:39:38 CEST 2020

Hi Andy,

-----"Andy Shevchenko" <andriy.shevchenko at> schrieb: -----
> Betreff: Re: [PATCH v3 13/29] dts: Add a binding for hid-over-i2c
> On Tue, Apr 07, 2020 at 08:58:13PM -0600, Simon Glass wrote:
> > On Tue, 31 Mar 2020 at 13:25, Wolfgang Wallner
> > <wolfgang.wallner at> wrote:
> > > >An: u-boot at
> > > >Von: "Simon Glass" <sjg at>
> > > >Datum: 31.03.2020 01:14
> > > >Kopie: "Andy Shevchenko" <andriy.shevchenko at>,
> > > >"Wolfgang Wallner" <wolfgang.wallner at>, "Leif
> > > >Lindholm" <leif at>, "Simon Glass" <sjg at>
> > > >Betreff: [PATCH v3 14/29] acpi: Add a binding for ACPI settings in
> > > >the device tree
> > > The _DSD-method for "PRP0001"-devices in ACPI allows to use Devicetree
> > > properties inside ACPI, especially it allows to re-use Devicetree's
> > > "compatible"-property. But this is for a different use case (using Devicetree
> > > properties inside ACPI, not add ACPI properties in Devicetree).
> Before we are going further with this here is a BIG CAVEAT.
> PRP0001   MUST NOT be used in production devices.
> This has been derived solely for debugging / pre-production testing / etc
> purposes. The real devices must have an official ACPI _HID.

Thanks for pointing this out! I was not aware of this.
I have tried to understand how the PRP0001 is meant to be used, but could not
find sufficient documentation. The best document I could find is
Documentation/firmware-guide/acpi/enumeration.rst in the Linux kernel, and
as far as I can tell the constraint that you mention is also not described

Do you know any other resources regarding PRP0001, e.g. some kind of

If PRP0001 is only for debugging, then I must also have misunderstood the
Linux "device-property" API (define in include/linux/property.h).
There are some presentations available on the internet, e.g. [1], that I
understand like PRP0001 + "device-property" API provide a way do access data
from either Devicetree or ACPI, depending on what kind of platform you are on.

regards, Wolfgang


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