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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 8 Aug 2018 12:45:29 +0300
Message-ID: <CAHp75VdmrwZ4P0xrOOqpJaU7iuKS8zXGcRTg4zLrofZLdcb=8Q@mail.gmail.com>
Subject: Re: [PATCH] spi: dw: support 4-16 bits per word
To:     Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Cc:     Mark Brown <broonie@kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Aug 8, 2018 at 10:14 AM, Simon Goldschmidt
<simon.k.r.goldschmidt@gmail.com> wrote:
> The spi-dw driver currently only supports 8 or 16 bits per word.
>
> Since the hardware supports 4-16 bits per word, adapt the driver
> to also support this.
>
> Tested on socfpga cyclone5 with a 9-bit SPI display.

> +       if ((transfer->bits_per_word < 4) || (transfer->bits_per_word > 16))
> +               return -EINVAL;

> +       if (transfer->bits_per_word <= 8) {
>                 dws->n_bytes = 1;
>                 dws->dma_width = 1;
> -       } else if (transfer->bits_per_word == 16) {
> +       } else {
>                 dws->n_bytes = 2;
>                 dws->dma_width = 2;
>         }

Now these can be just

n_bytes = round_up(8);
dma_width = round_up(8);

-- 
With Best Regards,
Andy Shevchenko