Re: [PATCH] mmc: block: Use .card_busy() to detect busy state in card_busy_detect

[Shawn Lin <shawn.lin@rock-chips.com>]

Hi Christian

On 2021/6/8 14:28, Christian Löhle wrote:
> Hey Shawn,
> You're assuming a card not signalling busy indicates TRAN state, and set the state manually,
> but a card might not be pulling DAT lines in PROG state.

Refer to JESD84-B51 for emmc spec, section 6.5.13 clearly says that. And
SD spec V4 also has a similar statement in section 4.3.4.

So I guess if that was the case you point out, most of all operations in
mmc_ops.c would suffer from this.


> I will send a patch later that reworks card_busy_detect, as there are some issues
> with some command sequences in practice. I'd ask to wait with the patch until then.
> 
> Regards,
> Christian
> 
> 
> From: Shawn Lin <shawn.lin@rock-chips.com>
> Sent: Monday, June 7, 2021 11:18 AM
> To: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: linux-mmc@vger.kernel.org <linux-mmc@vger.kernel.org>; Shawn Lin <shawn.lin@rock-chips.com>
> Subject: [PATCH] mmc: block: Use .card_busy() to detect busy state in card_busy_detect
>   
> No need to send CMD13 if host driver supports .card_busy().
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
> 
>   drivers/mmc/core/block.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 88f4c215..23623a9 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -417,10 +417,17 @@ static int card_busy_detect(struct mmc_card *card, unsigned int timeout_ms,
>           unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
>           int err = 0;
>           u32 status;
> +       bool busy;
>   
>           do {
>                   bool done = time_after(jiffies, timeout);
>   
> +               if (card->host->ops->card_busy) {
> +                       busy = card->host->ops->card_busy(card->host);
> +                       status = busy ? 0 : R1_READY_FOR_DATA | R1_STATE_TRAN << 9;
> +                       goto cb;
> +               }
> +
>                   err = __mmc_send_status(card, &status, 5);
>                   if (err) {
>                           dev_err(mmc_dev(card->host),
> @@ -442,6 +449,7 @@ static int card_busy_detect(struct mmc_card *card, unsigned int timeout_ms,
>                                    __func__, status);
>                           return -ETIMEDOUT;
>                   }
> +cb:
>           } while (!mmc_ready_for_data(status));
>   
>           return err;
>