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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Thu, 4 Mar 2021 10:33:51 +0100
Message-ID: <CAK8P3a0Wi5YrTFvfMopzBPdWrZi03abDhL_PanJ4HZ=Ycx8s3g@mail.gmail.com>
Subject: Re: [PATCH 4/8] spidev: Add Pensando CPLD compatible
To:     Brad Larson <brad@pensando.io>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Mark Brown <broonie@kernel.org>,
        Serge Semin <fancer.lancer@gmail.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Olof Johansson <olof@lixom.net>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Thu, Mar 4, 2021 at 4:41 AM Brad Larson <brad@pensando.io> wrote:
>
> Pensando Elba SoC platforms have a SPI connected CPLD
> for platform management.
>
> Signed-off-by: Brad Larson <brad@pensando.io>
> ---
>  drivers/spi/spidev.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
> index 8cb4d923aeaa..8b285852ce82 100644
> --- a/drivers/spi/spidev.c
> +++ b/drivers/spi/spidev.c
> @@ -683,6 +683,7 @@ static const struct of_device_id spidev_dt_ids[] = {
>         { .compatible = "dh,dhcom-board" },
>         { .compatible = "menlo,m53cpld" },
>         { .compatible = "cisco,spi-petra" },
> +       { .compatible = "pensando,cpld" },
>         {},
>  };

This does not seem appropriate, I think a platform management driver should
have a proper kernel abstraction instead of a user passthrough.

As mentioned elsewhere, it also needs to be way more specific. If this
is a programmable block, the compatible string might in fact need to
contain both a board identifier and a revision number for the programmable
logic, to ensure that the driver knows how to talk to it.

      Arnd