[U-Boot] [PATCH 4/6] mmc: Continue polling MMC card for OCR only if it is still not ready

[Troy Kisky <troy.kisky@boundarydevices.com>]

On 3/19/2015 6:51 PM, Peng.Fan at freescale.com wrote:
> Hi, Andrew
> 
> There is already a patch to fix this issue.
> Patchwork: https://patchwork.ozlabs.org/patch/451775/
> 
> Regards,
> Peng.
> 
> -----Original Message-----
> From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Andrew Gabbasov
> Sent: Thursday, March 19, 2015 8:44 PM
> To: u-boot at lists.denx.de
> Subject: [U-Boot] [PATCH 4/6] mmc: Continue polling MMC card for OCR only if it is still not ready
> 
> Some MMC cards come to ready state quite quickly, so that the respective flag appears to be set in mmc_send_op_cond already. In this case trying to continue polling the card with CMD1 in mmc_complete_op_cond is incorrect and may lead to unpredictable results. So check the flag before polling and skip it appropriately.
> 
> Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
> ---
>  drivers/mmc/mmc.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index d073d79..42af47c 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -403,15 +403,17 @@ static int mmc_complete_op_cond(struct mmc *mmc)
>  	int err;
>  
>  	mmc->op_cond_pending = 0;
> -	start = get_timer(0);
> -	do {
> -		err = mmc_send_op_cond_iter(mmc, 1);
> -		if (err)
> -			return err;
> -		if (get_timer(start) > timeout)
> -			return UNUSABLE_ERR;
> -		udelay(100);
> -	} while (!(mmc->ocr & OCR_BUSY));
> +	if (!(mmc->ocr & OCR_BUSY)) {
> +		start = get_timer(0);
> +		do {
> +			err = mmc_send_op_cond_iter(mmc, 1);
> +			if (err)
> +				return err;
> +			if (get_timer(start) > timeout)
> +				return UNUSABLE_ERR;
> +			udelay(100);
> +		} while (!(mmc->ocr & OCR_BUSY));
> +	}
>  
>  	if (mmc_host_is_spi(mmc)) { /* read OCR for spi */
>  		cmd.cmdidx = MMC_CMD_SPI_READ_OCR;
> --


Here's another patch that solves the problem a little earlier. It has this disadvantage of being
slightly bigger,
though it makes the code look better.


https://github.com/boundarydevices/u-boot-imx6/commit/c0260ca


I'll ack any version as they all seem to solve the problem.

Troy