[U-Boot] [PATCH] mmc: fsl_esdhc: increase data transaction timeout to 500ms

[york sun]

On 12/29/2015 10:27 PM, Yangbo Lu wrote:
> The MMC spec says "It is strongly recommended for hosts to implement
> more than 500ms timeout value even if the card indicates the 250ms
> maximum busy length."  Even the previous value of 300ms is known to
> be insufficient for some cards. So, increase the timeout to 500ms.
> 
> Signed-off-by: Yangbo Lu <yangbo.lu at nxp.com>
> ---
>  drivers/mmc/fsl_esdhc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> index c5054d6..12820cf 100644
> --- a/drivers/mmc/fsl_esdhc.c
> +++ b/drivers/mmc/fsl_esdhc.c
> @@ -252,8 +252,15 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
>  	 * Rounding up to next power of 2
>  	 * => timeout + 13 = log2(mmc->clock/4) + 1
>  	 * => timeout + 13 = fls(mmc->clock/4)
> +	 *
> +	 * However, the MMC spec "It is strongly recommended for hosts to
> +	 * implement more than 500ms timeout value even if the card
> +	 * indicates the 250ms maximum busy length."  Even the previous
> +	 * value of 300ms is known to be insufficient for some cards.
> +	 * So, we use
> +	 * => timeout + 13 = fls(mmc->clock/2)
>  	 */
> -	timeout = fls(mmc->clock/4);
> +	timeout = fls(mmc->clock/2);
>  	timeout -= 13;
>  
>  	if (timeout > 14)
> 

Pantelis,

With your ack, I can take this in, unless you want to merge it.

York