@@ -1202,6 +1202,122 @@ static int mmc_blk_err_check(struct mmc_card *card,
return MMC_BLK_SUCCESS;
}
+/*
+ * mmc_blk_reinsert_req() - re-insert request back to the scheduler
+ * @areq: request to re-insert.
+ *
+ * Request may be packed or single. When fails to reinsert request, it will be
+ * requeued to the the dispatch queue.
+ */
+static void mmc_blk_reinsert_req(struct mmc_async_req *areq)
+{
+ struct request *prq;
+ int ret = 0;
+ struct mmc_queue_req *mq_rq;
+ struct request_queue *q;
+
+ mq_rq = container_of(areq, struct mmc_queue_req, mmc_active);
+ q = mq_rq->req->q;
+ if (mq_rq->cmd_type != MMC_PACKED_NONE) {
+ while (!list_empty(&mq_rq->packed->list)) {
+ /* return requests in reverse order */
+ prq = list_entry_rq(mq_rq->packed->list.prev);
+ list_del_init(&prq->queuelist);
+ spin_lock_irq(q->queue_lock);
+ ret = blk_reinsert_request(q, prq);
+ if (ret) {
+ blk_requeue_request(q, prq);
+ spin_unlock_irq(q->queue_lock);
+ goto reinsert_error;
+ }
+ spin_unlock_irq(q->queue_lock);
+ }
+ } else {
+ spin_lock_irq(q->queue_lock);
+ ret = blk_reinsert_request(q, mq_rq->req);
+ if (ret)
+ blk_requeue_request(q, mq_rq->req);
+ spin_unlock_irq(q->queue_lock);
+ }
+ return;
+
+reinsert_error:
+ pr_err("%s: blk_reinsert_request() failed (%d)",
+ mq_rq->req->rq_disk->disk_name, ret);
+ /*
+ * -EIO will be reported for this request and rest of packed->list.
+ * Urgent request will be proceeded anyway, while upper layer
+ * responsibility to re-send failed requests
+ */
+ while (!list_empty(&mq_rq->packed->list)) {
+ prq = list_entry_rq(mq_rq->packed->list.next);
+ list_del_init(&prq->queuelist);
+ spin_lock_irq(q->queue_lock);
+ blk_requeue_request(q, prq);
+ spin_unlock_irq(q->queue_lock);
+ }
+}
+
+/*
+ * mmc_blk_update_interrupted_req() - update of the stopped request
+ * @card: the MMC card associated with the request.
+ * @areq: interrupted async request.
+ *
+ * Get stopped request state from card and update successfully done part of
+ * the request by setting packed_fail_idx. The packed_fail_idx is index of
+ * first uncompleted request in packed request list, for non-packed request
+ * packed_fail_idx remains unchanged.
+ *
+ * Returns: MMC_BLK_SUCCESS for success, MMC_BLK_ABORT otherwise
+ */
+static int mmc_blk_update_interrupted_req(struct mmc_card *card,
+ struct mmc_async_req *areq)
+{
+ int ret = MMC_BLK_SUCCESS;
+ u8 *ext_csd;
+ int correctly_done;
+ struct mmc_queue_req *mq_rq = container_of(areq, struct mmc_queue_req,
+ mmc_active);
+ struct request *prq;
+ u8 req_index = 0;
+ struct mmc_packed *packed;
+
+ if (mq_rq->cmd_type == MMC_PACKED_NONE)
+ return MMC_BLK_SUCCESS;
+
+ ext_csd = kmalloc(512, GFP_KERNEL);
+ if (!ext_csd)
+ return MMC_BLK_ABORT;
+
+ /* get correctly programmed sectors number from card */
+ ret = mmc_send_ext_csd(card, ext_csd);
+ if (ret) {
+ pr_err("%s: error %d reading ext_csd\n",
+ mmc_hostname(card->host), ret);
+ ret = MMC_BLK_ABORT;
+ goto exit;
+ }
+ correctly_done = card->ext_csd.data_sector_size *
+ (ext_csd[EXT_CSD_CORRECTLY_PRG_SECTORS_NUM + 0] << 0 |
+ ext_csd[EXT_CSD_CORRECTLY_PRG_SECTORS_NUM + 1] << 8 |
+ ext_csd[EXT_CSD_CORRECTLY_PRG_SECTORS_NUM + 2] << 16 |
+ ext_csd[EXT_CSD_CORRECTLY_PRG_SECTORS_NUM + 3] << 24);
+
+ packed = mq_rq->packed;
+ list_for_each_entry(prq, &packed->list, queuelist) {
+ if ((correctly_done - (int)blk_rq_bytes(prq)) < 0) {
+ /* prq is not successfull */
+ packed->idx_failure = req_index;
+ break;
+ }
+ correctly_done -= blk_rq_bytes(prq);
+ req_index++;
+ }
+exit:
+ kfree(ext_csd);
+ return ret;
+}
+
static int mmc_blk_packed_err_check(struct mmc_card *card,
struct mmc_async_req *areq)
{
@@ -1410,7 +1526,11 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
}
mqrq->mmc_active.mrq = &brq->mrq;
+ mqrq->mmc_active.cmd_flags = req->cmd_flags;
mqrq->mmc_active.err_check = mmc_blk_err_check;
+ mqrq->mmc_active.reinsert_req = mmc_blk_reinsert_req;
+ mqrq->mmc_active.update_interrupted_req =
+ mmc_blk_update_interrupted_req;
mmc_queue_bounce_pre(mqrq);
}
@@ -1619,6 +1739,11 @@ static void mmc_blk_packed_hdr_wrq_prep(struct mmc_queue_req *mqrq,
mqrq->mmc_active.mrq = &brq->mrq;
mqrq->mmc_active.err_check = mmc_blk_packed_err_check;
+ mqrq->mmc_active.cmd_flags = req->cmd_flags;
+
+ mqrq->mmc_active.reinsert_req = mmc_blk_reinsert_req;
+ mqrq->mmc_active.update_interrupted_req =
+ mmc_blk_update_interrupted_req;
mmc_queue_bounce_pre(mqrq);
}
@@ -1779,6 +1904,20 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
mmc_queue_bounce_post(mq_rq);
switch (status) {
+ case MMC_BLK_URGENT:
+ if (mq_rq->cmd_type != MMC_PACKED_NONE) {
+ /* complete successfully transmitted part */
+ if (mmc_blk_end_packed_req(mq_rq))
+ /* process for not transmitted part */
+ mmc_blk_reinsert_req(areq);
+ } else {
+ mmc_blk_reinsert_req(areq);
+ }
+
+ mq->flags |= MMC_QUEUE_URGENT_REQUEST;
+ ret = 0;
+ break;
+ case MMC_BLK_URGENT_DONE:
case MMC_BLK_SUCCESS:
case MMC_BLK_PARTIAL:
/*
@@ -1958,13 +2097,23 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
}
out:
+ /*
+ * packet burst is over, when one of the following occurs:
+ * - no more requests and new request notification is not in progress
+ * - urgent notification in progress and current request is not urgent
+ * (all existing requests completed or reinserted to the block layer)
+ */
if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
- (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK)))
+ (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK)) ||
+ ((mq->flags & MMC_QUEUE_URGENT_REQUEST) &&
+ !(mq->mqrq_cur->req->cmd_flags & REQ_URGENT)))
+
/*
* Release host when there are no more requests
* and after special request(discard, flush) is done.
* In case sepecial request, there is no reentry to
* the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
+ * In case urgent request is pending, no release host
*/
mmc_put_card(card);
return ret;
@@ -69,8 +69,18 @@ static int mmc_queue_thread(void *d)
cmd_flags = req ? req->cmd_flags : 0;
mq->issue_fn(mq, req);
if (mq->flags & MMC_QUEUE_NEW_REQUEST) {
- mq->flags &= ~MMC_QUEUE_NEW_REQUEST;
continue; /* fetch again */
+ } else if ((mq->flags & MMC_QUEUE_URGENT_REQUEST) &&
+ (mq->mqrq_cur->req &&
+ !(mq->mqrq_cur->req->cmd_flags & REQ_URGENT))) {
+ /*
+ * clean current request when urgent request
+ * processing in progress and current request is
+ * not urgent (all existing requests completed
+ * or reinserted to the block layer
+ */
+ mq->mqrq_cur->brq.mrq.data = NULL;
+ mq->mqrq_cur->req = NULL;
}
/*
@@ -93,6 +103,7 @@ static int mmc_queue_thread(void *d)
set_current_state(TASK_RUNNING);
break;
}
+ mq->card->host->context_info.is_urgent = false;
up(&mq->thread_sem);
schedule();
down(&mq->thread_sem);
@@ -141,6 +152,42 @@ static void mmc_request_fn(struct request_queue *q)
wake_up_process(mq->thread);
}
+/*
+ * mmc_urgent_request() - Urgent MMC request handler.
+ * @q: request queue.
+ *
+ * This is called when block layer has urgent request for delivery. When mmc
+ * context is waiting for the current request to complete, it will be awaken,
+ * current request may be interrupted and re-inserted back to block device
+ * request queue. The next fetched request should be urgent request, this
+ * will be ensured by block i/o scheduler.
+ */
+static void mmc_urgent_request(struct request_queue *q)
+{
+ unsigned long flags;
+ struct mmc_queue *mq = q->queuedata;
+ struct mmc_context_info *cntx;
+
+ if (!mq) {
+ mmc_request_fn(q);
+ return;
+ }
+ cntx = &mq->card->host->context_info;
+
+ /* critical section with mmc_wait_data_done() */
+ spin_lock_irqsave(&cntx->lock, flags);
+
+ /* do stop flow only when mmc thread is waiting for done */
+ if (mq->mqrq_cur->req || mq->mqrq_prev->req) {
+ cntx->is_urgent = true;
+ spin_unlock_irqrestore(&cntx->lock, flags);
+ wake_up_interruptible(&cntx->wait);
+ } else {
+ spin_unlock_irqrestore(&cntx->lock, flags);
+ mmc_request_fn(q);
+ }
+}
+
static struct scatterlist *mmc_alloc_sg(int sg_len, int *err)
{
struct scatterlist *sg;
@@ -203,6 +250,11 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
if (!mq->queue)
return -ENOMEM;
+ if ((host->caps2 & MMC_CAP2_STOP_REQUEST) &&
+ host->ops->stop_request &&
+ mq->card->ext_csd.hpi)
+ blk_urgent_request(mq->queue, mmc_urgent_request);
+
mq->mqrq_cur = mqrq_cur;
mq->mqrq_prev = mqrq_prev;
mq->queue->queuedata = mq;
@@ -48,8 +48,9 @@ struct mmc_queue {
struct task_struct *thread;
struct semaphore thread_sem;
unsigned int flags;
-#define MMC_QUEUE_SUSPENDED (1 << 0)
-#define MMC_QUEUE_NEW_REQUEST (1 << 1)
+#define MMC_QUEUE_SUSPENDED (1 << 0)
+#define MMC_QUEUE_NEW_REQUEST (1 << 1)
+#define MMC_QUEUE_URGENT_REQUEST (1 << 2)
int (*issue_fn)(struct mmc_queue *, struct request *);
void *data;
@@ -372,6 +372,86 @@ static int __mmc_start_req(struct mmc_host *host, struct mmc_request *mrq)
}
/*
+ * mmc_should_stop_curr_req() - check for stop flow rationality
+ * @host: MMC host running request.
+ *
+ * Check possibility to interrupt current running request
+ * Returns true in case it is worth to stop transfer,
+ * false otherwise
+ */
+static bool mmc_should_stop_curr_req(struct mmc_host *host)
+{
+ int remainder;
+
+ if (host->areq->cmd_flags & REQ_URGENT ||
+ !(host->areq->cmd_flags & REQ_WRITE) ||
+ (host->areq->cmd_flags & REQ_FUA))
+ return false;
+
+ remainder = (host->ops->get_xfer_remain) ?
+ host->ops->get_xfer_remain(host) : -1;
+ return (remainder > 0);
+}
+
+/*
+ * mmc_stop_request() - Stops current running request
+ * @host: MMC host to prepare the command.
+ *
+ * Triggers stop flow in the host driver and sends CMD12 (stop command) to the
+ * card. Sends HPI to get the card out of R1_STATE_PRG immediately
+ *
+ * Returns 0 when success, error propagated otherwise
+ */
+static int mmc_stop_request(struct mmc_host *host)
+{
+ struct mmc_command cmd = {0};
+ struct mmc_card *card = host->card;
+ int err = 0;
+ u32 status;
+
+ if (!host->ops->stop_request || !card->ext_csd.hpi) {
+ pr_warn("%s: host ops stop_request() or HPI not supported\n",
+ mmc_hostname(host));
+ return -ENOTSUPP;
+ }
+ err = host->ops->stop_request(host);
+ if (err) {
+ pr_err("%s: Call to host->ops->stop_request() failed (%d)\n",
+ mmc_hostname(host), err);
+ goto out;
+ }
+
+ cmd.opcode = MMC_STOP_TRANSMISSION;
+ cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
+ err = mmc_wait_for_cmd(host, &cmd, 0);
+ if (err) {
+ err = mmc_send_status(card, &status);
+ if (err) {
+ pr_err("%s: Get card status fail\n",
+ mmc_hostname(card->host));
+ goto out;
+ }
+ switch (R1_CURRENT_STATE(status)) {
+ case R1_STATE_DATA:
+ case R1_STATE_RCV:
+ pr_err("%s: CMD12 fails with error (%d)\n",
+ mmc_hostname(host), err);
+ goto out;
+ default:
+ break;
+ }
+ }
+ err = mmc_interrupt_hpi(card);
+ if (err) {
+ pr_err("%s: mmc_interrupt_hpi() failed (%d)\n",
+ mmc_hostname(host), err);
+ goto out;
+ }
+out:
+ return err;
+}
+
+/*
* mmc_wait_for_data_req_done() - wait for request completed
* @host: MMC host to prepare the command.
* @mrq: MMC request to wait for
@@ -388,14 +468,18 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
{
struct mmc_command *cmd;
struct mmc_context_info *context_info = &host->context_info;
+ bool pending_is_urgent = false;
+ bool is_urgent = false;
int err;
unsigned long flags;
while (1) {
wait_event_interruptible(context_info->wait,
(context_info->is_done_rcv ||
- context_info->is_new_req));
+ context_info->is_new_req ||
+ context_info->is_urgent));
spin_lock_irqsave(&context_info->lock, flags);
+ is_urgent = context_info->is_urgent;
context_info->is_waiting_last_req = false;
spin_unlock_irqrestore(&context_info->lock, flags);
if (context_info->is_done_rcv) {
@@ -407,6 +491,21 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
mmc_card_removed(host->card)) {
err = host->areq->err_check(host->card,
host->areq);
+ if (pending_is_urgent || is_urgent) {
+ /*
+ * all the success/partial operations
+ * are done in an addition to handling
+ * the urgent request
+ */
+ if ((err == MMC_BLK_PARTIAL) ||
+ (err == MMC_BLK_SUCCESS))
+ err = pending_is_urgent ?
+ MMC_BLK_URGENT_DONE
+ : MMC_BLK_URGENT;
+
+ /* reset is_urgent for next request */
+ context_info->is_urgent = false;
+ }
break; /* return err */
} else {
pr_info("%s: req failed (CMD%u): %d, retrying...\n",
@@ -415,14 +514,60 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
cmd->retries--;
cmd->error = 0;
host->ops->request(host, mrq);
- continue; /* wait for done/new event again */
+ /*
+ * ignore urgent flow, request retry has greater
+ * priority than urgent flow
+ */
+ context_info->is_urgent = false;
+ /* wait for done/new/urgent event again */
+ continue;
}
- } else if (context_info->is_new_req) {
+ } else if (context_info->is_new_req && !is_urgent) {
context_info->is_new_req = false;
if (!next_req) {
err = MMC_BLK_NEW_REQUEST;
break; /* return err */
}
+ } else {
+ /*
+ * The case when block layer sent next urgent
+ * notification before it receives end_io on
+ * the current
+ */
+ BUG_ON(pending_is_urgent == true);
+
+ context_info->is_urgent = false;
+ context_info->is_new_req = false;
+ if (mmc_should_stop_curr_req(host)) {
+ err = mmc_stop_request(host);
+ if (err && !context_info->is_done_rcv) {
+ err = MMC_BLK_ABORT;
+ break;
+ }
+ /* running request has finished at this point */
+ if (context_info->is_done_rcv) {
+ err = host->areq->err_check(host->card,
+ host->areq);
+ context_info->is_done_rcv = false;
+ break; /* return err */
+ }
+
+ err = host->areq->update_interrupted_req(
+ host->card, host->areq);
+ if (!err)
+ err = MMC_BLK_URGENT;
+ break; /* return err */
+ } else {
+ /*
+ * The flow will back to wait for is_done_rcv,
+ * but in this case original is_urgent cleared.
+ * Mark pending_is_urgent to differentiate the
+ * case, when is_done_rcv and is_urgent really
+ * concurrent.
+ */
+ pending_is_urgent = true;
+ continue; /* wait for done/new/urgent event */
+ }
}
}
return err;
@@ -529,14 +674,40 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
int err = 0;
int start_err = 0;
struct mmc_async_req *data = host->areq;
+ unsigned long flags;
+ bool is_urgent;
/* Prepare a new request */
- if (areq)
+ if (areq) {
+ /*
+ * start waiting here for possible interrupt
+ * because mmc_pre_req() taking long time
+ */
mmc_pre_req(host, areq->mrq, !host->areq);
+ }
if (host->areq) {
- err = mmc_wait_for_data_req_done(host, host->areq->mrq, areq);
- if (err == MMC_BLK_NEW_REQUEST) {
+ err = mmc_wait_for_data_req_done(host, host->areq->mrq,
+ areq);
+ if (err == MMC_BLK_URGENT || err == MMC_BLK_URGENT_DONE) {
+ mmc_post_req(host, host->areq->mrq, 0);
+ host->areq = NULL;
+ if (areq) {
+ if (!(areq->cmd_flags & REQ_URGENT)) {
+ areq->reinsert_req(areq);
+ mmc_post_req(host, areq->mrq, 0);
+ } else {
+ start_err = __mmc_start_data_req(host,
+ areq->mrq);
+ if (start_err)
+ mmc_post_req(host, areq->mrq,
+ -EINVAL);
+ else
+ host->areq = areq;
+ }
+ }
+ goto exit;
+ } else if (err == MMC_BLK_NEW_REQUEST) {
if (error)
*error = err;
/*
@@ -554,9 +725,27 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
(host->areq->mrq->cmd->resp[0] & R1_EXCEPTION_EVENT))
mmc_start_bkops(host->card, true);
}
+ if (!err && areq) {
+ /* urgent notification may come again */
+ spin_lock_irqsave(&host->context_info.lock, flags);
+ is_urgent = host->context_info.is_urgent;
+ host->context_info.is_urgent = false;
+ spin_unlock_irqrestore(&host->context_info.lock, flags);
- if (!err && areq)
- start_err = __mmc_start_data_req(host, areq->mrq);
+ if (!is_urgent || (areq->cmd_flags & REQ_URGENT)) {
+ start_err = __mmc_start_data_req(host, areq->mrq);
+ } else {
+ /* previous request was done */
+ err = MMC_BLK_URGENT_DONE;
+ if (host->areq) {
+ mmc_post_req(host, host->areq->mrq, 0);
+ host->areq = NULL;
+ }
+ areq->reinsert_req(areq);
+ mmc_post_req(host, areq->mrq, 0);
+ goto exit;
+ }
+ }
if (host->areq)
mmc_post_req(host, host->areq->mrq, 0);
@@ -570,6 +759,7 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
else
host->areq = areq;
+exit:
if (error)
*error = err;
return data;
@@ -196,6 +196,7 @@ struct sdio_cis {
struct mmc_host;
struct sdio_func;
struct sdio_func_tuple;
+struct mmc_queue;
#define SDIO_MAX_FUNCS 7
@@ -209,6 +210,8 @@ enum mmc_blk_status {
MMC_BLK_ECC_ERR,
MMC_BLK_NOMEDIUM,
MMC_BLK_NEW_REQUEST,
+ MMC_BLK_URGENT,
+ MMC_BLK_URGENT_DONE,
};
/* The number of MMC physical partitions. These consist of:
@@ -527,5 +530,5 @@ extern void mmc_unregister_driver(struct mmc_driver *);
extern void mmc_fixup_device(struct mmc_card *card,
const struct mmc_fixup *table);
-
+extern void mmc_blk_disable_wr_packing(struct mmc_queue *mq);
#endif /* LINUX_MMC_CARD_H */
@@ -139,6 +139,8 @@ struct mmc_host_ops {
int (*select_drive_strength)(unsigned int max_dtr, int host_drv, int card_drv);
void (*hw_reset)(struct mmc_host *host);
void (*card_event)(struct mmc_host *host);
+ int (*stop_request)(struct mmc_host *host);
+ unsigned int (*get_xfer_remain)(struct mmc_host *host);
};
struct mmc_card;
@@ -147,11 +149,18 @@ struct device;
struct mmc_async_req {
/* active mmc request */
struct mmc_request *mrq;
+ unsigned int cmd_flags; /* copied from struct request */
+
/*
* Check error status of completed mmc request.
* Returns 0 if success otherwise non zero.
*/
int (*err_check) (struct mmc_card *, struct mmc_async_req *);
+ /* Reinserts request back to the block layer */
+ void (*reinsert_req) (struct mmc_async_req *);
+ /* update what part of request is not done (packed_fail_idx) */
+ int (*update_interrupted_req) (struct mmc_card *,
+ struct mmc_async_req *);
};
/**
@@ -176,7 +185,10 @@ struct mmc_slot {
* mmc_context_info - synchronization details for mmc context
* @is_done_rcv wake up reason was done request
* @is_new_req wake up reason was new request
- * @is_waiting_last_req mmc context waiting for single running request
+ * @is_waiting_last_req is true, when 1 request running on the bus and
+ * NULL fetched as second request. MMC_BLK_NEW_REQUEST
+ * notification will wake up mmc thread from waiting.
+ * @is_urgent wake up reason was urgent request
* @wait wait queue
* @lock lock to protect data fields
*/
@@ -184,6 +196,7 @@ struct mmc_context_info {
bool is_done_rcv;
bool is_new_req;
bool is_waiting_last_req;
+ bool is_urgent;
wait_queue_head_t wait;
spinlock_t lock;
};
@@ -282,6 +295,7 @@ struct mmc_host {
#define MMC_CAP2_NO_PRESCAN_POWERUP (1 << 14) /* Don't power up before scan */
#define MMC_CAP2_SANITIZE (1 << 15) /* Support Sanitize */
+#define MMC_CAP2_STOP_REQUEST (1 << 14) /* Allow stop ongoing request */
mmc_pm_flag_t pm_caps; /* supported pm features */
#ifdef CONFIG_MMC_CLKGATE
@@ -321,6 +321,7 @@ struct _mmc_csd {
#define EXT_CSD_PWR_CL_200_360 237 /* RO */
#define EXT_CSD_PWR_CL_DDR_52_195 238 /* RO */
#define EXT_CSD_PWR_CL_DDR_52_360 239 /* RO */
+#define EXT_CSD_CORRECTLY_PRG_SECTORS_NUM 242 /* RO, 4 bytes */
#define EXT_CSD_BKOPS_STATUS 246 /* RO */
#define EXT_CSD_POWER_OFF_LONG_TIME 247 /* RO */
#define EXT_CSD_GENERIC_CMD6_TIME 248 /* RO */
Urgent request notification stops currently running transaction on bus. In order to decrease a latency of a prioritized requests (aka Urgent request), we might want to stop the transmission of a running "low priority" request in order to handle the Urgent request. The urgency of the request is decided by the block layer I/O scheduler. When the block layer notifies the MMC layer of an urgent request and if the MMC layer is blocked on current request to complete, it will be woken up. The decision on whether to stop an ongoing transfer is taken according to several parameters, one of them being the number of bytes already transferred for ongoing transfer by host controller so far. To calculate how many bytes were successfully programmed before stop, CORRECTLY_PRG_SECTORS_NUM[245:242] is parsed from EXT_CSD register. The remainder of the stopped request (and next prepared request in case it exists) are re-inserted back to the I/O scheduler to be re-scheduled later. In case it is decided not to stop the ongoing transfer, MMC context will wait for normal completion of the ongoing transfer, then already prepared next request (if it exists) will be re-inserted back into block layer and the urgent request will be fetched. URGENT_REQUEST handling has the following dependencies: 1. Host controller driver should support mmc_host op named "stop_request" 2. Block I/O scheduler should support re-insert API 3. eMMC card should support HPI (High Priority Interrupt) command If any of the above dependencies are not met then urgent request mechanism will not become operational. Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>