Re: [PATCH 4/4] mmc: core: Don't use ->card_busy() and CMD13 in combination when polling

[Adrian Hunter <adrian.hunter@intel.com>]

On 20/10/16 11:19, Ulf Hansson wrote:
> When polling for busy after sending a MMC_SWITCH command, both the optional
> ->card_busy() callback and CMD13 are being used in conjunction.
> 
> This doesn't make sense. Instead it's more reasonable to rely solely on the
> ->card_busy() callback when it exists. Let's change that and instead use
> the CMD13 as a fall-back. In this way we avoid sending CMD13, unless it's
> really needed.
> 
> Within this context, let's also take the opportunity to make some
> additional clean-ups and clarifications to the related code.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>  drivers/mmc/core/mmc_ops.c | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index a84a880..481bbdb 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -495,34 +495,32 @@ static int mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms,
>  	timeout = jiffies + msecs_to_jiffies(timeout_ms) + 1;
>  	do {
>  		/*
> -		 * Due to the possibility of being preempted after
> -		 * sending the status command, check the expiration
> -		 * time first.
> +		 * Due to the possibility of being preempted while polling,
> +		 * check the expiration time first.
>  		 */
>  		expired = time_after(jiffies, timeout);
> -		if (send_status) {
> +
> +		if (host->ops->card_busy) {
> +			busy = host->ops->card_busy(host);

I didn't really have time to look at these patches, sorry :-(.  But this
loop looks like it could use a cond_resched()

> +		} else {
>  			err = __mmc_send_status(card, &status, ignore_crc);
>  			if (err)
>  				return err;
> -		}
> -		if (host->ops->card_busy) {
> -			if (!host->ops->card_busy(host))
> -				break;
> -			busy = true;
> +			busy = R1_CURRENT_STATE(status) == R1_STATE_PRG;
>  		}
>  
> -		/* Timeout if the device never leaves the program state. */
> -		if (expired &&
> -		    (R1_CURRENT_STATE(status) == R1_STATE_PRG || busy)) {
> -			pr_err("%s: Card stuck in programming state! %s\n",
> +		/* Timeout if the device still remains busy. */
> +		if (expired && busy) {
> +			pr_err("%s: Card stuck being busy! %s\n",
>  				mmc_hostname(host), __func__);
>  			return -ETIMEDOUT;
>  		}
> -	} while (R1_CURRENT_STATE(status) == R1_STATE_PRG || busy);
> +	} while (busy);
>  
> -	err = mmc_switch_status_error(host, status);
> +	if (host->ops->card_busy && send_status)
> +		return mmc_switch_status(card);
>  
> -	return err;
> +	return mmc_switch_status_error(host, status);
>  }
>  
>  /**
>