[PATCH] mmc: retry CMD1 in mmc_send_op_cond() until the eMMC is ready

[Peng Fan]

> Subject: [PATCH] mmc: retry CMD1 in mmc_send_op_cond() until the eMMC
> is ready
> 
> From: Haibo Chen <haibo.chen at nxp.com>
> 
> According to eMMC specification v5.1 section 6.4.3, we should issue
> CMD1 repeatedly in the idle state until the eMMC is ready even if
> mmc_send_op_cond() send CMD1 with argument = 0. Otherwise some
> eMMC devices seems to enter the inactive mode after
> mmc_complete_op_cond() issued CMD0 when the eMMC device is busy. This
> patch also align with Linux 5.7.
> 
> Signed-off-by: Haibo Chen <haibo.chen at nxp.com>
> ---
>  drivers/mmc/mmc.c | 41 +++++++++++++++++++++++++++++++++--------
>  1 file changed, 33 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index
> 523c055967..509549756b 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -664,21 +664,46 @@ static int mmc_send_op_cond_iter(struct mmc
> *mmc, int use_arg)
> 
>  static int mmc_send_op_cond(struct mmc *mmc)  {
> +	struct mmc_cmd cmd;
>  	int err, i;
> +	int timeout = 1000;
> +	ulong start;
> 
>  	/* Some cards seem to need this */
>  	mmc_go_idle(mmc);
> 
> - 	/* Asking to the card its capabilities */
> -	for (i = 0; i < 2; i++) {
> -		err = mmc_send_op_cond_iter(mmc, i != 0);
> +	cmd.cmdidx = MMC_CMD_SEND_OP_COND;
> +	cmd.resp_type = MMC_RSP_R3;
> +	cmd.cmdarg = 0;
> +
> +	start = get_timer(0);
> +	/*
> +	 * According to eMMC specification v5.1 section 6.4.3, we
> +	 * should issue CMD1 repeatedly in the idle state until
> +	 * the eMMC is ready. Otherwise some eMMC devices seem to enter
> +	 * the inactive mode after mmc_complete_op_cond() issued CMD0
> when
> +	 * the eMMC device is busy.
> +	 */

Could we just extend the previous for loop to fix the issue?
Your piece code duplicate much of the code and changed
the original behavior.

> +	while (1) {
> +		err = mmc_send_cmd(mmc, &cmd, NULL);
>  		if (err)
>  			return err;
> -
> -		/* exit if not busy (flag seems to be inverted) */
> -		if (mmc->ocr & OCR_BUSY)
> -			break;
> +		if (mmc_host_is_spi(mmc)) {
> +			if (!(cmd.response[0] & (1 << 0)))
> +				break;
> +		} else {
> +			mmc->ocr = cmd.response[0];
> +			/* exit if not busy (flag seems to be inverted) */
> +			if (mmc->ocr & OCR_BUSY)
> +				break;
> +		}
> +		if (get_timer(start) > timeout)
> +			return -EOPNOTSUPP;

TIMEOUT, please.

> +		udelay(100);

This will change the original behavior by adding a delay.

> +		if (!mmc_host_is_spi(mmc))
> +			cmd.cmdarg = cmd.response[0] | (1 << 30);

Do we need "1 << 30" ?

>  	}
> +
>  	mmc->op_cond_pending = 1;
>  	return 0;
>  }
> @@ -691,7 +716,7 @@ static int mmc_complete_op_cond(struct mmc
> *mmc)
>  	int err;
> 
>  	mmc->op_cond_pending = 0;
> -	if (!(mmc->ocr & OCR_BUSY)) {
> +	if (mmc->ocr & OCR_BUSY) {

When card not go out busy, it means card not
finish power up seq. Why drop !?

>  		/* Some cards seem to need this */
>  		mmc_go_idle(mmc);
> 
> --

Would the following patch help?

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 523c055967..d3a0538cdb 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -665,12 +665,15 @@ static int mmc_send_op_cond_iter(struct mmc *mmc, int use_arg)
 static int mmc_send_op_cond(struct mmc *mmc)
 {
        int err, i;
+       int timeout = 1000;
+       ulong start;

        /* Some cards seem to need this */
        mmc_go_idle(mmc);

+       start = get_timer(0);
        /* Asking to the card its capabilities */
-       for (i = 0; i < 2; i++) {
+       for (i = 0; ; i++) {
                err = mmc_send_op_cond_iter(mmc, i != 0);
                if (err)
                        return err;
@@ -678,6 +681,9 @@ static int mmc_send_op_cond(struct mmc *mmc)
                /* exit if not busy (flag seems to be inverted) */
                if (mmc->ocr & OCR_BUSY)
                        break;
+
+               if (get_timer(start) > timeout)
+                       return -ETIMEDOUT;
        }
        mmc->op_cond_pending = 1;
        return 0;

Thanks,
Peng.
> 2.17.1