[U-Boot] [PATCH] mmc: dw_mmc: Calculate timeout from transfer length

[Simon Glass]

Hi Marek,

On Sat, 23 Mar 2019 at 11:55, Marek Vasut <marex at denx.de> wrote:
>
> The current 4-minute data transfer timeout is misleading and broken.
> Instead of such a long wait, calculate the timeout duration based on
> the length of the data transfer. The current formula is the transfer
> length in bits, divided by a multiplication of bus frequency in Hz,
> bus width, DDR mode and converted the mSec. The value is bounded from
> the bottom to 1000 mSec.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Jaehoon Chung <jh80.chung at samsung.com>
> Cc: Simon Glass <sjg at chromium.org>
> ---
>  drivers/mmc/dw_mmc.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
> index 93a836eac3..8278f1dacb 100644
> --- a/drivers/mmc/dw_mmc.c
> +++ b/drivers/mmc/dw_mmc.c
> @@ -116,20 +116,29 @@ static int dwmci_fifo_ready(struct dwmci_host *host, u32 bit, u32 *len)
>
>  static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data)
>  {
> +       struct mmc *mmc = host->mmc;
>         int ret = 0;
> -       u32 timeout = 240000;
> -       u32 mask, size, i, len = 0;
> +       u32 timeout, mask, size, i, len = 0;
>         u32 *buf = NULL;
>         ulong start = get_timer(0);
>         u32 fifo_depth = (((host->fifoth_val & RX_WMARK_MASK) >>
>                             RX_WMARK_SHIFT) + 1) * 2;
>
> -       size = data->blocksize * data->blocks / 4;
> +       size = data->blocksize * data->blocks;
>         if (data->flags == MMC_DATA_READ)
>                 buf = (unsigned int *)data->dest;
>         else
>                 buf = (unsigned int *)data->src;
>
> +       timeout = size * 8 * 1000;      /* counting in bits and msec */
> +       timeout *= 2;                   /* wait twice as long */
> +       timeout /= mmc->clock;
> +       timeout /= mmc->bus_width;
> +       timeout /= mmc->ddr_mode ? 2 : 1;
> +       timeout = (timeout < 1000) ? 1000 : timeout;

Can you put all this in a function (like calc_timeout_ms(size, clock,
bus_width, ddr_mode)) that returns the correct timeout given the
parameters? That would provide a modicum of documentation.

> +
> +       size /= 4;
> +
>         for (;;) {
>                 mask = dwmci_readl(host, DWMCI_RINTSTS);
>                 /* Error during data transfer. */
> --
> 2.20.1
>

Regards,
Simon