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Subject[PATCH v3 08/12] mmc: add handling for two parallel block requests in issue_rw_rq
Date
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
isuue_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.forlin@linaro.org>
---
drivers/mmc/card/block.c | 157 +++++++++++++++++++++++++++++++++++++++-------
drivers/mmc/card/queue.c | 11 ++--
2 files changed, 138 insertions(+), 30 deletions(-)
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 9444243..a6ff546 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -516,24 +516,75 @@ static enum mmc_blk_status mmc_blk_get_status(struct mmc_blk_request *brq,

}

-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 *brqc = &mq->mqrq_cur->brq;
+ struct mmc_blk_request *brqp = &mq->mqrq_prev->brq;
+ struct mmc_queue_req *mqrqp = mq->mqrq_prev;
+ struct request *rqp = mqrqp->req;
+ int ret = 0;
+ int disable_multi = 0;
enum mmc_blk_status status;

- mmc_claim_host(card->host);
+ if (!rqc && !rqp)
+ return 0;

- do {
- mmc_blk_rw_rq_prep(mq->mqrq_cur, card, disable_multi, mq);
- mmc_wait_for_req(card->host, &brq->mrq);
+ if (rqc) {
+ /* Claim host for the first request in a serie of requests */
+ if (!rqp)
+ mmc_claim_host(card->host);

- mmc_queue_bounce_post(mq->mqrq_cur);
- status = mmc_blk_get_status(brq, req, card, md);
+ /* Prepare a new request */
+ mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
+ mmc_pre_req(card->host, &brqc->mrq, !rqp);
+ }
+ do {
+ /*
+ * If there is an ongoing request, indicated by rqp, wait for
+ * it to finish before starting a new one.
+ */
+ if (rqp)
+ mmc_wait_for_req_done(&brqp->mrq);
+ else {
+ /* start a new asynchronous request */
+ mmc_start_req(card->host, &brqc->mrq);
+ goto out;
+ }
+ status = mmc_blk_get_status(brqp, rqp, card, md);
+ if (status != MMC_BLK_SUCCESS) {
+ mmc_post_req(card->host, &brqp->mrq, -EINVAL);
+ mmc_queue_bounce_post(mqrqp);
+ if (rqc)
+ mmc_post_req(card->host, &brqc->mrq, -EINVAL);
+ }

switch (status) {
+ case MMC_BLK_SUCCESS:
+ /*
+ * A block was successfully transferred.
+ */
+
+ /*
+ * All data is transferred without errors.
+ * Defer mmc post processing and _blk_end_request
+ * until after the new request is started.
+ */
+ if (blk_rq_bytes(rqp) == brqp->data.bytes_xfered)
+ break;
+
+ mmc_post_req(card->host, &brqp->mrq, 0);
+ mmc_queue_bounce_post(mqrqp);
+
+ spin_lock_irq(&md->lock);
+ ret = __blk_end_request(rqp, 0,
+ brqp->data.bytes_xfered);
+ spin_unlock_irq(&md->lock);
+
+ if (rqc)
+ mmc_post_req(card->host, &brqc->mrq, -EINVAL);
+ break;
case MMC_BLK_CMD_ERR:
goto cmd_err;
break;
@@ -548,27 +599,73 @@ 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(rqp, -EIO, brqp->data.blksz);
spin_unlock_irq(&md->lock);
-
+ if (rqc && !ret)
+ mmc_pre_req(card->host, &brqc->mrq, false);
break;
- case MMC_BLK_SUCCESS:
+ }
+
+ 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(mqrqp, card, disable_multi, mq);
+ mmc_pre_req(card->host, &brqp->mrq, true);
+ mmc_start_req(card->host, &brqp->mrq);
+ if (rqc)
+ mmc_pre_req(card->host, &brqc->mrq, false);
}
} while (ret);

- mmc_release_host(card->host);
+ /* Previous request is completed, start the new request if any */
+ if (rqc)
+ mmc_start_req(card->host, &brqc->mrq);
+
+ /*
+ * Post process the previous request while the new request is active.
+ * In case of error the reuqest is already ended.
+ */
+ if (status == MMC_BLK_SUCCESS) {
+ mmc_post_req(card->host, &brqp->mrq, 0);
+ mmc_queue_bounce_post(mqrqp);
+
+ spin_lock_irq(&md->lock);
+ ret = __blk_end_request(rqp, 0, brqp->data.bytes_xfered);
+ spin_unlock_irq(&md->lock);
+
+ if (ret) {
+ /* If this happen it is a bug */
+ printk(KERN_ERR "[%s] BUG: rq_bytes %d xfered %d\n",
+ __func__, blk_rq_bytes(rqp),
+ brqp->data.bytes_xfered);
+ goto cmd_err;
+ }
+ }
+
+ /* 1 indicates one request has been completed */
+ ret = 1;
+ out:
+ /*
+ * TODO: Find out if it is OK to only release host after the
+ * last request. For the last request the current request
+ * is NULL, which means no requests are pending.
+ */
+ /* Release host for the last request in a serie of requests */
+ if (!rqc)
+ mmc_release_host(card->host);

- return 1;
+ /* Current request becomes previous request and vice versa. */
+ mqrqp->brq.mrq.data = NULL;
+ mqrqp->req = NULL;
+ mq->mqrq_prev = mq->mqrq_cur;
+ mq->mqrq_cur = mqrqp;
+
+ return ret;

cmd_err:
+
/*
* If this is an SD card and we're writing, we can first
* mark the known good sectors as ok.
@@ -583,12 +680,12 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
blocks = mmc_sd_num_wr_blocks(card);
if (blocks != (u32)-1) {
spin_lock_irq(&md->lock);
- ret = __blk_end_request(req, 0, blocks << 9);
+ ret = __blk_end_request(rqp, 0, blocks << 9);
spin_unlock_irq(&md->lock);
}
} else {
spin_lock_irq(&md->lock);
- ret = __blk_end_request(req, 0, brq->data.bytes_xfered);
+ ret = __blk_end_request(rqp, 0, brqp->data.bytes_xfered);
spin_unlock_irq(&md->lock);
}

@@ -596,15 +693,27 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)

spin_lock_irq(&md->lock);
while (ret)
- ret = __blk_end_request(req, -EIO, blk_rq_cur_bytes(req));
+ ret = __blk_end_request(rqp, -EIO, blk_rq_cur_bytes(rqp));
spin_unlock_irq(&md->lock);

+ if (rqc) {
+ mmc_claim_host(card->host);
+ mmc_pre_req(card->host, &brqc->mrq, false);
+ mmc_start_req(card->host, &brqc->mrq);
+ }
+
+ /* Current request becomes previous request and vice versa. */
+ mqrqp->brq.mrq.data = NULL;
+ mqrqp->req = NULL;
+ mq->mqrq_prev = mq->mqrq_cur;
+ mq->mqrq_cur = mqrqp;
+
return 0;
}

static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
{
- if (req->cmd_flags & REQ_DISCARD) {
+ if (req && req->cmd_flags & REQ_DISCARD) {
if (req->cmd_flags & REQ_SECURE)
return mmc_blk_issue_secdiscard_rq(mq, req);
else
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index eef3510..70a0871 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -59,19 +59,18 @@ static int mmc_queue_thread(void *d)
mq->mqrq_cur->req = req;
spin_unlock_irq(q->queue_lock);

+ set_current_state(TASK_RUNNING);
+ mq->issue_fn(mq, req);
if (!req) {
- if (kthread_should_stop()) {
- set_current_state(TASK_RUNNING);
+ if (kthread_should_stop())
break;
- }
+
+ set_current_state(TASK_INTERRUPTIBLE);
up(&mq->thread_sem);
schedule();
down(&mq->thread_sem);
continue;
}
- set_current_state(TASK_RUNNING);
-
- mq->issue_fn(mq, req);
} while (1);
up(&mq->thread_sem);

--
1.7.4.1


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