linux-kernel - Re: [PATCH RFC 1/3] spi: Allow SPI controller override device buswidth

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Date:   Mon, 2 Mar 2020 19:51:29 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     John Garry <john.garry@...wei.com>
Cc:     Mark Brown <broonie@...nel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        MTD Maling List <linux-mtd@...ts.infradead.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH RFC 1/3] spi: Allow SPI controller override device buswidth

Hi John,

On Fri, Feb 28, 2020 at 4:23 PM John Garry <john.garry@...wei.com> wrote:
> Currently ACPI firmware description for a SPI device does not have any
> method to describe the data buswidth on the board.
>
> So even through the controller and device may support higher modes than
> standard SPI, it cannot be assumed that the board does - as such, that
> device is limited to standard SPI in such a circumstance.
>
> As a workaround, allow the controller driver supply buswidth override bits,
> which are used inform the core code that the controller driver knows the
> buswidth supported on that board for that device.

Just wondering: can't the controller just override this (e.g. in the .setuup()
callback) without having to touch the generic code?

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