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Date:   Thu, 27 Aug 2020 12:32:16 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        kuldip dwivedi <kuldip.dwivedi@puresoftware.com>,
        linux-spi <linux-spi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Qiang Zhao <qiang.zhao@nxp.com>,
        Pankaj Bansal <pankaj.bansal@nxp.com>,
        Varun Sethi <V.Sethi@nxp.com>,
        tanveer <tanveer.alam@puresoftware.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH] spi: spi-fsl-dspi: Add ACPI support
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On Thu, Aug 27, 2020 at 12:06:57AM +0300, Vladimir Oltean wrote:
> On Wed, Aug 26, 2020 at 09:45:47PM +0100, Mark Brown wrote:
> > On Wed, Aug 26, 2020 at 11:41:08PM +0300, Vladimir Oltean wrote:

> > > Something doesn't look right about PRP0001, what's the catch?

> > Microsoft decided not to implement support for it in Windows, it's
> > essentially there for embedded style x86 platforms running Linux so they
> > don't need to reimplement so many wheels and can just reuse existing DT
> > bindings but it causes problems if you want to run Windows (and possibly
> > some of the enterprise Linux distros, I can't remember if any of them
> > had concerns about it) on the platform.

> So if a silicon vendor doesn't care about Windows, what incentive does
> it have to even register an official ACPI/PNP ID for its devices?

Not that there's any registration process or anything, there's some
namespacing but that's it, but the main thing would just be keeping the
ACPI bindings and DT bindings separate.  ACPI has some strong opinions
on how systems are built and described so while you can use the PRP0001
stuff to parse DT bindings on an ACPI system it doesn't alway fit well,
and there are some things where you just plain shouldn't use PRP0001
since the ACPI and DT models for that sort of device diverge so strongly.

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