[U-Boot] [PATCH] fsl_esdhc: Correcting esdhc timeout counter calculation

[Kumar Gala]

On Feb 24, 2011, at 2:53 AM, Kumar Gala wrote:

> From: Priyanka Jain <Priyanka.Jain at freescale.com>
> 
> - Timeout counter value is set as DTOCV bits in SYSCTL register
>  For counter value set as x,
>  Timeout period = (2^(13+x))/SD_CLOCK
> 
> - As per 4.6.2.2 section of SD Card specification v2.00, host should
>  cofigure timeout period value to minimum 250 msec.
> 
> - SD_CLOCK = mmc->trans_speed
> 
> - Calculating x based on
>  250 msec = (2^(13+x))/mmc->trans_speed
> 
> Signed-off-by: Priyanka Jain <Priyanka.Jain at freescale.com>
> Signed-off-by: Andy Fleming <afleming at freescale.com>
> Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
> ---
> drivers/mmc/fsl_esdhc.c |    5 ++++-
> 1 files changed, 4 insertions(+), 1 deletions(-)

Stefano,

Can you test this on iMX to make sure we didnt break anything there.

> 
> diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> index c6de751..6f8a09d 100644
> --- a/drivers/mmc/fsl_esdhc.c
> +++ b/drivers/mmc/fsl_esdhc.c
> @@ -210,7 +210,10 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
> 	esdhc_write32(&regs->blkattr, data->blocks << 16 | data->blocksize);
> 
> 	/* Calculate the timeout period for data transactions */
> -	timeout = fls(mmc->tran_speed/10) - 1;
> +	/* Timeout period = (2^(13+timeout))/mmc->trans_speed
> +	 * Timeout period should be minimum 250msec as per SD Card spec
> +	 */
> +	timeout = fls(mmc->tran_speed/4);
> 	timeout -= 13;
> 
> 	if (timeout > 14)
> -- 
> 1.7.2.3
> 
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