linux-kernel - Re: [PATCH] spi: rockchip: configure CTRLR1 according to size and data frame

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Message-ID: <CAMuHMdVT77+am8RfAAyruZxqB=CN0++YQM6gcbHDG_7mmdkwDw@mail.gmail.com>
Date:   Wed, 16 Aug 2017 14:16:04 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Huibin Hong <huibin.hong@...k-chips.com>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        Tao Huang <huangtao@...k-chips.com>,
        Mark Brown <broonie@...nel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: rockchip: configure CTRLR1 according to size and
 data frame

Hi Huibin,

On Wed, Aug 16, 2017 at 4:12 AM, Huibin Hong <huibin.hong@...k-chips.com> wrote:
> CTRLR1 is number of data frames, when rx only.
> When data frame is 8 bit, CTRLR1 is len-1.
> When data frame is 16 bit, CTRLR1 is (len/2)-1.

What does the last "else" case correspond to?

> Signed-off-by: Huibin Hong <huibin.hong@...k-chips.com>
> ---
>
>  drivers/spi/spi-rockchip.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
> index 0b4a52b..6b1bac8 100644
> --- a/drivers/spi/spi-rockchip.c
> +++ b/drivers/spi/spi-rockchip.c
> @@ -568,7 +568,13 @@ static void rockchip_spi_config(struct rockchip_spi *rs)
>
>         writel_relaxed(cr0, rs->regs + ROCKCHIP_SPI_CTRLR0);
>
> -       writel_relaxed(rs->len - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
> +       if (rs->n_bytes == 1)
> +               writel_relaxed(rs->len - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
> +       else if (rs->n_bytes == 2)
> +               writel_relaxed((rs->len / 2) - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
> +       else
> +               writel_relaxed((rs->len * 2) - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
> +
>         writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_TXFTLR);
>         writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_RXFTLR);

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