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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 26 Aug 2020 22:36:15 +0300
Message-ID: <CAHp75VetYbnOHv3LQhq4Gvs1CFe8LnZPzFAVoNmBi5DyAmZ9Jg@mail.gmail.com>
Subject: Re: [PATCH] spi: spi-fsl-dspi: Add ACPI support
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     kuldip dwivedi <kuldip.dwivedi@puresoftware.com>,
        Mark Brown <broonie@kernel.org>,
        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>
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On Wed, Aug 26, 2020 at 10:34 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Sat, Aug 22, 2020 at 9:37 PM Vladimir Oltean <olteanv@gmail.com> wrote:
> > On Fri, Aug 21, 2020 at 06:40:29PM +0530, kuldip dwivedi wrote:
>
> > Just noticed this now.
> > So for device tree, spi-fsl-dspi supports the following compatibles:
> >
> > fsl,vf610-dspi
> > fsl,ls1021a-v1.0-dspi
> > fsl,ls1012a-dspi
> > fsl,ls1028a-dspi
> > fsl,ls1043a-dspi
> > fsl,ls1046a-dspi
> > fsl,ls2080a-dspi
> > fsl,ls2085a-dspi
> > fsl,lx2160a-dspi
> >
> > Depending on the compatible string, the driver knows whether to use DMA
> > or XSPI mode, and what the FIFO size is.

FIFO size can be read from the property (or better if you can derive
it directly from HW, like DesignWare does).
DMA is just defined by FixedDMA resources (your platform with DMA
provides them, otherwise no such resources).

> > Now, of course not all of the above SoCs are going to support ACPI, but
> > it is reasonable to expect that more than one will. And in that case,
> > the driver should still be able to know on what SoC it's running,
> > because for example LS1043A doesn't support DMA, and LS2085A doesn't
> > support XSPI.
> >
> > How is this dealt with in ACPI?
>
> Theoretically you may declare your HID in the same / similar way as
> PRP0001 and use same compatible strings and all other DT properties
> (when they make sense and not duplicate ACPI functionality).
> But better if ACPI people can tell you (I Cc'ed Rafael and ACPI
> mailing list) if it is gonna work.


-- 
With Best Regards,
Andy Shevchenko