Change mmc_blk_issue_rw_rq() to become asynchronous.
The execution flow looks like this:
The mmc-queue calls issue_rw_rq(), which sends the request
to the host and returns back to the mmc-queue. The mmc-queue calls
issue_rw_rq() again with a new request. This new request is prepared,
in isuue_rw_rq(), then it waits for the active request to complete before
pushing it to the host. When to mmc-queue is empty it will call
isuue_rw_rq() with req=NULL to finish off the active request
without starting a new request.

Signed-off-by: Per Forlin <per.for...@linaro.org>
---
 drivers/mmc/card/block.c |  121 +++++++++++++++++++++++++++++++++-------------
 drivers/mmc/card/queue.c |   17 +++++--
 drivers/mmc/card/queue.h |    1 +
 3 files changed, 101 insertions(+), 38 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 6a84a75..66db77a 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -108,6 +108,7 @@ static DEFINE_MUTEX(open_lock);
 
 enum mmc_blk_status {
        MMC_BLK_SUCCESS = 0,
+       MMC_BLK_PARTIAL,
        MMC_BLK_RETRY,
        MMC_BLK_DATA_ERR,
        MMC_BLK_CMD_ERR,
@@ -668,14 +669,16 @@ static inline void mmc_apply_rel_rw(struct 
mmc_blk_request *brq,
        }
 }
 
-static enum mmc_blk_status mmc_blk_err_check(struct mmc_blk_request *brq,
-                                            struct request *req,
-                                            struct mmc_card *card,
-                                            struct mmc_blk_data *md)
+static int mmc_blk_err_check(struct mmc_card *card,
+                            struct mmc_async_req *areq)
 {
        struct mmc_command cmd;
        u32 status = 0;
        enum mmc_blk_status ret = MMC_BLK_SUCCESS;
+       struct mmc_queue_req *mq_mrq = container_of(areq, struct mmc_queue_req,
+                                                   mmc_active);
+       struct mmc_blk_request *brq = &mq_mrq->brq;
+       struct request *req = mq_mrq->req;
 
        /*
         * Check for errors here, but don't jump to cmd_err
@@ -770,7 +773,11 @@ static enum mmc_blk_status mmc_blk_err_check(struct 
mmc_blk_request *brq,
                else
                        ret = MMC_BLK_DATA_ERR;
        }
-out:
+
+       if (ret == MMC_BLK_SUCCESS &&
+           blk_rq_bytes(req) != brq->data.bytes_xfered)
+               ret = MMC_BLK_PARTIAL;
+ out:
        return ret;
 }
 
@@ -901,27 +908,59 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
                brq->data.sg_len = i;
        }
 
+       mqrq->mmc_active.mrq = &brq->mrq;
+       mqrq->mmc_active.err_check = mmc_blk_err_check;
+
        mmc_queue_bounce_pre(mqrq);
 }
 
-static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
+static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc)
 {
        struct mmc_blk_data *md = mq->data;
        struct mmc_card *card = md->queue.card;
-       struct mmc_blk_request *brq = &mq->mqrq_cur->brq;
-       int ret = 1, disable_multi = 0;
+       struct mmc_blk_request *brq;
+       int ret = 1;
+       int disable_multi = 0;
        enum mmc_blk_status status;
+       struct mmc_queue_req *mq_rq;
+       struct request *req;
+       struct mmc_async_req *areq;
+
+       if (!rqc && !mq->mqrq_prev->req)
+               goto out;
 
        do {
-               mmc_blk_rw_rq_prep(mq->mqrq_cur, card, disable_multi, mq);
-               mmc_wait_for_req(card->host, &brq->mrq);
+               if (rqc) {
+                       mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
+                       areq = &mq->mqrq_cur->mmc_active;
+               } else
+                       areq = NULL;
+               areq = mmc_start_req(card->host, areq, (int *) &status);
+               if (!areq)
+                       goto out;
 
-               mmc_queue_bounce_post(mq->mqrq_cur);
-               status = mmc_blk_err_check(brq, req, card, md);
+               mq_rq = container_of(areq, struct mmc_queue_req, mmc_active);
+               brq = &mq_rq->brq;
+               req = mq_rq->req;
+               mmc_queue_bounce_post(mq_rq);
 
                switch (status) {
-               case MMC_BLK_CMD_ERR:
-                       goto cmd_err;
+               case MMC_BLK_SUCCESS:
+               case MMC_BLK_PARTIAL:
+                       /*
+                        * A block was successfully transferred.
+                        */
+                       spin_lock_irq(&md->lock);
+                       ret = __blk_end_request(req, 0,
+                                               brq->data.bytes_xfered);
+                       spin_unlock_irq(&md->lock);
+                       if (status == MMC_BLK_SUCCESS && ret) {
+                               /* If this happen it is a bug */
+                               printk(KERN_ERR "%s BUG rq_tot %d d_xfer %d\n",
+                                      __func__, blk_rq_bytes(req),
+                                      brq->data.bytes_xfered);
+                               goto cmd_err;
+                       }
                        break;
                case MMC_BLK_RETRY:
                        disable_multi = 1;
@@ -934,36 +973,41 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, 
struct request *req)
                         * read a single sector.
                         */
                        spin_lock_irq(&md->lock);
-                       ret = __blk_end_request(req, -EIO,
-                                               brq->data.blksz);
+                       ret = __blk_end_request(req, -EIO, brq->data.blksz);
                        spin_unlock_irq(&md->lock);
-
+                       if (!ret)
+                               goto start_new_req;
                        break;
-               case MMC_BLK_SUCCESS:
+               case MMC_BLK_CMD_ERR:
+                       ret = 1;
+                       goto cmd_err;
+                       break;
+               }
+
+               if (ret) {
                        /*
-                        * A block was successfully transferred.
+                        * In case of a none complete request
+                        * prepare it again and resend.
                         */
-                       spin_lock_irq(&md->lock);
-                       ret = __blk_end_request(req, 0, brq->data.bytes_xfered);
-                       spin_unlock_irq(&md->lock);
-                       break;
+                       mmc_blk_rw_rq_prep(mq_rq, card, disable_multi, mq);
+                       mmc_start_req(card->host, &mq_rq->mmc_active, NULL);
                }
        } while (ret);
 
        return 1;
-
+ out:
+       return 0;
  cmd_err:
-       /*
-        * If this is an SD card and we're writing, we can first
-        * mark the known good sectors as ok.
-        *
+       /*
+        * If this is an SD card and we're writing, we can first
+        * mark the known good sectors as ok.
+        *
         * If the card is not SD, we can still ok written sectors
         * as reported by the controller (which might be less than
         * the real number of written sectors, but never more).
         */
        if (mmc_card_sd(card)) {
                u32 blocks;
-
                blocks = mmc_sd_num_wr_blocks(card);
                if (blocks != (u32)-1) {
                        spin_lock_irq(&md->lock);
@@ -981,6 +1025,12 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, 
struct request *req)
                ret = __blk_end_request(req, -EIO, blk_rq_cur_bytes(req));
        spin_unlock_irq(&md->lock);
 
+ start_new_req:
+       if (rqc) {
+               mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
+               mmc_start_req(card->host, &mq->mqrq_cur->mmc_active, NULL);
+       }
+
        return 0;
 }
 
@@ -990,26 +1040,31 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct 
request *req)
        struct mmc_blk_data *md = mq->data;
        struct mmc_card *card = md->queue.card;
 
-       mmc_claim_host(card->host);
+       if (req && !mq->mqrq_prev->req)
+               /* claim host only for the first request */
+               mmc_claim_host(card->host);
+
        ret = mmc_blk_part_switch(card, md);
        if (ret) {
                ret = 0;
                goto out;
        }
 
-       if (req->cmd_flags & REQ_DISCARD) {
+       if (req && req->cmd_flags & REQ_DISCARD) {
                if (req->cmd_flags & REQ_SECURE)
                        ret = mmc_blk_issue_secdiscard_rq(mq, req);
                else
                        ret = mmc_blk_issue_discard_rq(mq, req);
-       } else if (req->cmd_flags & REQ_FLUSH) {
+       } else if (req && req->cmd_flags & REQ_FLUSH) {
                ret = mmc_blk_issue_flush(mq, req);
        } else {
                ret = mmc_blk_issue_rw_rq(mq, req);
        }
 
 out:
-       mmc_release_host(card->host);
+       if (!req)
+               /* release host only when there are no more requests */
+               mmc_release_host(card->host);
        return ret;
 }
 
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 0757a39..2d6696a 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -52,6 +52,7 @@ static int mmc_queue_thread(void *d)
        down(&mq->thread_sem);
        do {
                struct request *req = NULL;
+               struct mmc_queue_req *tmp;
 
                spin_lock_irq(q->queue_lock);
                set_current_state(TASK_INTERRUPTIBLE);
@@ -59,7 +60,10 @@ static int mmc_queue_thread(void *d)
                mq->mqrq_cur->req = req;
                spin_unlock_irq(q->queue_lock);
 
-               if (!req) {
+               if (req || mq->mqrq_prev->req) {
+                       set_current_state(TASK_RUNNING);
+                       mq->issue_fn(mq, req);
+               } else {
                        if (kthread_should_stop()) {
                                set_current_state(TASK_RUNNING);
                                break;
@@ -67,11 +71,14 @@ static int mmc_queue_thread(void *d)
                        up(&mq->thread_sem);
                        schedule();
                        down(&mq->thread_sem);
-                       continue;
                }
-               set_current_state(TASK_RUNNING);
 
-               mq->issue_fn(mq, req);
+               /* Current request becomes previous request and vice versa. */
+               mq->mqrq_prev->brq.mrq.data = NULL;
+               mq->mqrq_prev->req = NULL;
+               tmp = mq->mqrq_prev;
+               mq->mqrq_prev = mq->mqrq_cur;
+               mq->mqrq_cur = tmp;
        } while (1);
        up(&mq->thread_sem);
 
@@ -97,7 +104,7 @@ static void mmc_request(struct request_queue *q)
                return;
        }
 
-       if (!mq->mqrq_cur->req)
+       if (!mq->mqrq_cur->req && !mq->mqrq_prev->req)
                wake_up_process(mq->thread);
 }
 
diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h
index c8fb2dc..f937538 100644
--- a/drivers/mmc/card/queue.h
+++ b/drivers/mmc/card/queue.h
@@ -19,6 +19,7 @@ struct mmc_queue_req {
        char                    *bounce_buf;
        struct scatterlist      *bounce_sg;
        unsigned int            bounce_sg_len;
+       struct mmc_async_req    mmc_active;
 };
 
 struct mmc_queue {
-- 
1.7.4.1


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