[PATCH RFC 01/15] mmc: sunxi: Document host init sequence

[Ulf Hansson]

On 21 January 2016 at 06:26, Chen-Yu Tsai <wens at csie.org> wrote:
> sunxi_mmc_init_host() originated from Allwinner kernel sources. The
> magic numbers written to various registers was never documented.
>
> Add comments for values found in Allwinner user manuals.
>
> Signed-off-by: Chen-Yu Tsai <wens at csie.org>

Thanks, applied for next!

Kind regards
Uffe

> ---
>  drivers/mmc/host/sunxi-mmc.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
> index 83de82bceafc..cce5ca540857 100644
> --- a/drivers/mmc/host/sunxi-mmc.c
> +++ b/drivers/mmc/host/sunxi-mmc.c
> @@ -284,16 +284,28 @@ static int sunxi_mmc_init_host(struct mmc_host *mmc)
>         if (sunxi_mmc_reset_host(host))
>                 return -EIO;
>
> +       /*
> +        * Burst 8 transfers, RX trigger level: 7, TX trigger level: 8
> +        *
> +        * TODO: sun9i has a larger FIFO and supports higher trigger values
> +        */
>         mmc_writel(host, REG_FTRGL, 0x20070008);
> +       /* Maximum timeout value */
>         mmc_writel(host, REG_TMOUT, 0xffffffff);
> +       /* Unmask SDIO interrupt if needed */
>         mmc_writel(host, REG_IMASK, host->sdio_imask);
> +       /* Clear all pending interrupts */
>         mmc_writel(host, REG_RINTR, 0xffffffff);
> +       /* Debug register? undocumented */
>         mmc_writel(host, REG_DBGC, 0xdeb);
> +       /* Enable CEATA support */
>         mmc_writel(host, REG_FUNS, SDXC_CEATA_ON);
> +       /* Set DMA descriptor list base address */
>         mmc_writel(host, REG_DLBA, host->sg_dma);
>
>         rval = mmc_readl(host, REG_GCTRL);
>         rval |= SDXC_INTERRUPT_ENABLE_BIT;
> +       /* Undocumented, but found in Allwinner code */
>         rval &= ~SDXC_ACCESS_DONE_DIRECT;
>         mmc_writel(host, REG_GCTRL, rval);
>
> --
> 2.7.0.rc3
>