Commit 6966e609 authored by Ulf Hansson's avatar Ulf Hansson
Browse files

mmc: core: Avoid hogging the CPU while polling for busy after I/O writes 



When mmc_blk_card_busy() calls card_busy_detect() to poll for the card's
state with CMD13, this is done without any delays in between the commands
being sent.

Rather than fixing card_busy_detect() in this regards, let's instead
convert into using the common __mmc_poll_for_busy(), which also helps us to
avoid open-coding.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Reviewed-by: default avatarShawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/r/20210702134229.357717-4-ulf.hansson@linaro.org
parent 46810815

drivers/mmc/core/block.c

+29 −40
Original line number Diff line number Diff line
@@ -98,6 +98,11 @@ static int max_devices; 
static DEFINE_IDA(mmc_blk_ida);

static DEFINE_IDA(mmc_rpmb_ida);



struct mmc_blk_busy_data {

	struct mmc_card *card;

	u32 status;

};



/*

 * There is one mmc_blk_data per slot.

 */
@@ -417,42 +422,6 @@ static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr, 
	return 0;

}



static int card_busy_detect(struct mmc_card *card, unsigned int timeout_ms,

			    u32 *resp_errs)

{

	unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);

	int err = 0;

	u32 status;



	do {

		bool done = time_after(jiffies, timeout);



		err = __mmc_send_status(card, &status, 5);

		if (err) {

			dev_err(mmc_dev(card->host),

				"error %d requesting status\n", err);

			return err;

		}



		/* Accumulate any response error bits seen */

		if (resp_errs)

			*resp_errs |= status;



		/*

		 * Timeout if the device never becomes ready for data and never

		 * leaves the program state.

		 */

		if (done) {

			dev_err(mmc_dev(card->host),

				"Card stuck in wrong state! %s status: %#x\n",

				 __func__, status);

			return -ETIMEDOUT;

		}

	} while (!mmc_ready_for_data(status));



	return err;

}



static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,

			       struct mmc_blk_ioc_data *idata)

{
@@ -1852,28 +1821,48 @@ static inline bool mmc_blk_rq_error(struct mmc_blk_request *brq) 
	       brq->data.error || brq->cmd.resp[0] & CMD_ERRORS;

}



static int mmc_blk_busy_cb(void *cb_data, bool *busy)

{

	struct mmc_blk_busy_data *data = cb_data;

	u32 status = 0;

	int err;



	err = mmc_send_status(data->card, &status);

	if (err)

		return err;



	/* Accumulate response error bits. */

	data->status |= status;



	*busy = !mmc_ready_for_data(status);

	return 0;

}



static int mmc_blk_card_busy(struct mmc_card *card, struct request *req)

{

	struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);

	u32 status = 0;

	struct mmc_blk_busy_data cb_data;

	int err;



	if (mmc_host_is_spi(card->host) || rq_data_dir(req) == READ)

		return 0;



	err = card_busy_detect(card, MMC_BLK_TIMEOUT_MS, &status);

	cb_data.card = card;

	cb_data.status = 0;

	err = __mmc_poll_for_busy(card, MMC_BLK_TIMEOUT_MS, &mmc_blk_busy_cb,

				  &cb_data);



	/*

	 * Do not assume data transferred correctly if there are any error bits

	 * set.

	 */

	if (status & mmc_blk_stop_err_bits(&mqrq->brq)) {

	if (cb_data.status & mmc_blk_stop_err_bits(&mqrq->brq)) {

		mqrq->brq.data.bytes_xfered = 0;

		err = err ? err : -EIO;

	}



	/* Copy the exception bit so it will be seen later on */

	if (mmc_card_mmc(card) && status & R1_EXCEPTION_EVENT)

	if (mmc_card_mmc(card) && cb_data.status & R1_EXCEPTION_EVENT)

		mqrq->brq.cmd.resp[0] |= R1_EXCEPTION_EVENT;



	return err;

drivers/mmc/core/mmc_ops.c

+1 −0
Original line number Diff line number Diff line
@@ -510,6 +510,7 @@ int __mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms, 


	return 0;

}

EXPORT_SYMBOL_GPL(__mmc_poll_for_busy);



int mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms,

		      bool retry_crc_err, enum mmc_busy_cmd busy_cmd)