linux-kernel - Re: [PATCH v5 12/12] arm64: dts: ls1028a-rdb: Add a spidev node for the mikroBUS

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Message-ID: <CA+h21hpHeL08Gb36m1RNrE6agebZu7ygz9jFekOH7zGc9uLcSQ@mail.gmail.com>
Date:   Mon, 20 Apr 2020 21:10:27 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Mark Brown <broonie@...nel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Esben Haabendal <eha@...f.com>,
        Angelo Dureghello <angelo@...am.it>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Wei Chen <weic@...dia.com>, Mohamed Hosny <mhosny@...dia.com>,
        Michael Walle <michael@...le.cc>, peng.ma@....com
Subject: Re: [PATCH v5 12/12] arm64: dts: ls1028a-rdb: Add a spidev node for
 the mikroBUS

Hi Geert,

On Mon, 20 Apr 2020 at 21:07, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Vladimir,
>
> On Wed, Mar 18, 2020 at 1:17 AM Vladimir Oltean <olteanv@...il.com> wrote:
> > From: Vladimir Oltean <vladimir.oltean@....com>
> >
> > For debugging, it is useful to have access to the DSPI controller
> > signals. On the reference design board, these are exported to either the
> > mikroBUS1 or mikroBUS2 connector (according to the CPLD register
> > BRDCFG3[SPI3]).
> >
> > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
>
> Thanks for your patch!
>
> > --- a/arch/arm64/boot/dts/freescale/fsl-ls1028a-rdb.dts
> > +++ b/arch/arm64/boot/dts/freescale/fsl-ls1028a-rdb.dts
> > @@ -83,6 +83,20 @@
> >         };
> >  };
> >
> > +&dspi2 {
> > +       bus-num = <2>;
> > +       status = "okay";
> > +
> > +       /* mikroBUS1 */
> > +       spidev@0 {
>
> Please use generic node names, e.g. "dac@0".
>

It's not a DAC. It's really an unpopulated pin header. I would have
really liked to have access to that as a char device with the default
board DTS, via spidev. That being said, there are warnings to not use
the "spidev" compatible in device trees. So if what I want is not
possible, I'd rather drop the patch altogether.

> > +               compatible = "rohm,dh2228fv";
> > +               spi-max-frequency = <20000000>;
> > +               fsl,spi-cs-sck-delay = <100>;
> > +               fsl,spi-sck-cs-delay = <100>;
> > +               reg = <0>;
> > +       };
> > +};
> > +
> >  &esdhc {
> >         sd-uhs-sdr104;
> >         sd-uhs-sdr50;
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

Thanks,
-Vladimir