[PATCH V14 14/24] mmc: block: Add CQE support

Adrian Hunter
2017-11-21T13:42:40Z

Add CQE support to the block driver, including:
- optionally using DCMD for flush requests
- "manually" issuing discard requests
- issuing read / write requests to the CQE
- supporting block-layer timeouts
- handling recovery
- supporting re-tuning

CQE offers 25% - 50% better random multi-threaded I/O. There is a slight
(e.g. 2%) drop in sequential read speed but no observable change to sequential
write.

CQE automatically sends the commands to complete requests. However it only
supports reads / writes and so-called "direct commands" (DCMD). Furthermore
DCMD is limited to one command at a time, but discards require 3 commands.
That makes issuing discards through CQE very awkward, but some CQE's don't
support DCMD anyway. So for discards, the existing non-CQE approach is
taken, where the mmc core code issues the 3 commands one at a time i.e.
mmc_erase(). Where DCMD is used, is for issuing flushes.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
drivers/mmc/core/block.c | 150 +++++++++++++++++++++++++++++++++++++++++++-
drivers/mmc/core/block.h | 2 +
drivers/mmc/core/queue.c | 158 +++++++++++++++++++++++++++++++++++++++++++++--
drivers/mmc/core/queue.h | 18 ++++++
4 files changed, 322 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index a08d727d100b..2aacd3fa0d1a 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -111,6 +111,7 @@ struct mmc_blk_data {
#define MMC_BLK_WRITE BIT(1)
#define MMC_BLK_DISCARD BIT(2)
#define MMC_BLK_SECDISCARD BIT(3)
+#define MMC_BLK_CQE_RECOVERY BIT(4)

/*
* Only set in main mmc_blk_data associated
@@ -1785,6 +1786,138 @@ static void mmc_blk_data_prep(struct mmc_queue *mq, struct mmc_queue_req *mqrq,
*do_data_tag_p = do_data_tag;
}

+#define MMC_CQE_RETRIES 2
+
+static void mmc_blk_cqe_complete_rq(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = &mqrq->brq.mrq;
+ struct request_queue *q = req->q;
+ struct mmc_host *host = mq->card->host;
+ unsigned long flags;
+ bool put_card;
+ int err;
+
+ mmc_cqe_post_req(host, mrq);
+
+ if (mrq->cmd && mrq->cmd->error)
+ err = mrq->cmd->error;
+ else if (mrq->data && mrq->data->error)
+ err = mrq->data->error;
+ else
+ err = 0;
+
+ if (err) {
+ if (mqrq->retries++ < MMC_CQE_RETRIES)
+ blk_mq_requeue_request(req, true);
+ else
+ blk_mq_end_request(req, BLK_STS_IOERR);
+ } else if (mrq->data) {
+ if (blk_update_request(req, BLK_STS_OK, mrq->data->bytes_xfered))
+ blk_mq_requeue_request(req, true);
+ else
+ __blk_mq_end_request(req, BLK_STS_OK);
+ } else {
+ blk_mq_end_request(req, BLK_STS_OK);
+ }
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ mq->in_flight[mmc_issue_type(mq, req)] -= 1;
+
+ put_card = (mmc_tot_in_flight(mq) == 0);
+
+ mmc_cqe_check_busy(mq);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (!mq->cqe_busy)
+ blk_mq_run_hw_queues(q, true);
+
+ if (put_card)
+ mmc_put_card(mq->card, &mq->ctx);
+}
+
+void mmc_blk_cqe_recovery(struct mmc_queue *mq)
+{
+ struct mmc_card *card = mq->card;
+ struct mmc_host *host = card->host;
+ int err;
+
+ pr_debug("%s: CQE recovery start\n", mmc_hostname(host));
+
+ err = mmc_cqe_recovery(host);
+ if (err)
+ mmc_blk_reset(mq->blkdata, host, MMC_BLK_CQE_RECOVERY);
+ else
+ mmc_blk_reset_success(mq->blkdata, MMC_BLK_CQE_RECOVERY);
+
+ pr_debug("%s: CQE recovery done\n", mmc_hostname(host));
+}
+
+static void mmc_blk_cqe_req_done(struct mmc_request *mrq)
+{
+ struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
+ brq.mrq);
+ struct request *req = mmc_queue_req_to_req(mqrq);
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+
+ /*
+ * Block layer timeouts race with completions which means the normal
+ * completion path cannot be used during recovery.
+ */
+ if (mq->in_recovery)
+ mmc_blk_cqe_complete_rq(mq, req);
+ else
+ blk_mq_complete_request(req);
+}
+
+static int mmc_blk_cqe_start_req(struct mmc_host *host, struct mmc_request *mrq)
+{
+ mrq->done = mmc_blk_cqe_req_done;
+ mrq->recovery_notifier = mmc_cqe_recovery_notifier;
+
+ return mmc_cqe_start_req(host, mrq);
+}
+
+static struct mmc_request *mmc_blk_cqe_prep_dcmd(struct mmc_queue_req *mqrq,
+ struct request *req)
+{
+ struct mmc_blk_request *brq = &mqrq->brq;
+
+ memset(brq, 0, sizeof(*brq));
+
+ brq->mrq.cmd = &brq->cmd;
+ brq->mrq.tag = req->tag;
+
+ return &brq->mrq;
+}
+
+static int mmc_blk_cqe_issue_flush(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = mmc_blk_cqe_prep_dcmd(mqrq, req);
+
+ mrq->cmd->opcode = MMC_SWITCH;
+ mrq->cmd->arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+ (EXT_CSD_FLUSH_CACHE << 16) |
+ (1 << 8) |
+ EXT_CSD_CMD_SET_NORMAL;
+ mrq->cmd->flags = MMC_CMD_AC | MMC_RSP_R1B;
+
+ return mmc_blk_cqe_start_req(mq->card->host, mrq);
+}
+
+static int mmc_blk_cqe_issue_rw_rq(struct mmc_queue *mq, struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+
+ mmc_blk_data_prep(mq, mqrq, 0, NULL, NULL);
+
+ return mmc_blk_cqe_start_req(mq->card->host, &mqrq->brq.mrq);
+}
+
static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
struct mmc_card *card,
int disable_multi,
@@ -2059,7 +2192,10 @@ void mmc_blk_mq_complete(struct request *req)
{
struct mmc_queue *mq = req->q->queuedata;

- mmc_blk_mq_complete_rq(mq, req);
+ if (mq->use_cqe)
+ mmc_blk_cqe_complete_rq(mq, req);
+ else
+ mmc_blk_mq_complete_rq(mq, req);
}

static void mmc_blk_mq_poll_completion(struct mmc_queue *mq,
@@ -2218,6 +2354,9 @@ static int mmc_blk_mq_issue_rw_rq(struct mmc_queue *mq,

static int mmc_blk_wait_for_idle(struct mmc_queue *mq, struct mmc_host *host)
{
+ if (mq->use_cqe)
+ return host->cqe_ops->cqe_wait_for_idle(host);
+
return mmc_blk_rw_wait(mq, NULL);
}

@@ -2256,11 +2395,18 @@ enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req)
return MMC_REQ_FAILED_TO_START;
}
return MMC_REQ_FINISHED;
+ case MMC_ISSUE_DCMD:
case MMC_ISSUE_ASYNC:
switch (req_op(req)) {
+ case REQ_OP_FLUSH:
+ ret = mmc_blk_cqe_issue_flush(mq, req);
+ break;
case REQ_OP_READ:
case REQ_OP_WRITE:
- ret = mmc_blk_mq_issue_rw_rq(mq, req);
+ if (mq->use_cqe)
+ ret = mmc_blk_cqe_issue_rw_rq(mq, req);
+ else
+ ret = mmc_blk_mq_issue_rw_rq(mq, req);
break;
default:
WARN_ON_ONCE(1);
diff --git a/drivers/mmc/core/block.h b/drivers/mmc/core/block.h
index 6d34e87b18f6..f472ce5d5647 100644
--- a/drivers/mmc/core/block.h
+++ b/drivers/mmc/core/block.h
@@ -7,6 +7,8 @@

void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req);

+void mmc_blk_cqe_recovery(struct mmc_queue *mq);
+
enum mmc_issued;

enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req);
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index b9c2430e9292..d0eae15261d7 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -40,18 +40,142 @@ static int mmc_prep_request(struct request_queue *q, struct request *req)
return BLKPREP_OK;
}

+static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
+{
+ /* Allow only 1 DCMD at a time */
+ return mq->in_flight[MMC_ISSUE_DCMD];
+}
+
+void mmc_cqe_check_busy(struct mmc_queue *mq)
+{
+ if ((mq->cqe_busy & MMC_CQE_DCMD_BUSY) && !mmc_cqe_dcmd_busy(mq))
+ mq->cqe_busy &= ~MMC_CQE_DCMD_BUSY;
+
+ mq->cqe_busy &= ~MMC_CQE_QUEUE_FULL;
+}
+
+static inline bool mmc_cqe_can_dcmd(struct mmc_host *host)
+{
+ return host->caps2 & MMC_CAP2_CQE_DCMD;
+}
+
+enum mmc_issue_type mmc_cqe_issue_type(struct mmc_host *host,
+ struct request *req)
+{
+ switch (req_op(req)) {
+ case REQ_OP_DRV_IN:
+ case REQ_OP_DRV_OUT:
+ case REQ_OP_DISCARD:
+ case REQ_OP_SECURE_ERASE:
+ return MMC_ISSUE_SYNC;
+ case REQ_OP_FLUSH:
+ return mmc_cqe_can_dcmd(host) ? MMC_ISSUE_DCMD : MMC_ISSUE_SYNC;
+ default:
+ return MMC_ISSUE_ASYNC;
+ }
+}
+
enum mmc_issue_type mmc_issue_type(struct mmc_queue *mq, struct request *req)
{
+ struct mmc_host *host = mq->card->host;
+
+ if (mq->use_cqe)
+ return mmc_cqe_issue_type(host, req);
+
if (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_WRITE)
return MMC_ISSUE_ASYNC;

return MMC_ISSUE_SYNC;
}

+static void __mmc_cqe_recovery_notifier(struct mmc_queue *mq)
+{
+ if (!mq->recovery_needed) {
+ mq->recovery_needed = true;
+ schedule_work(&mq->recovery_work);
+ }
+}
+
+void mmc_cqe_recovery_notifier(struct mmc_request *mrq)
+{
+ struct mmc_queue_req *mqrq = container_of(mrq, struct mmc_queue_req,
+ brq.mrq);
+ struct request *req = mmc_queue_req_to_req(mqrq);
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __mmc_cqe_recovery_notifier(mq);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
+{
+ struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
+ struct mmc_request *mrq = &mqrq->brq.mrq;
+ struct mmc_queue *mq = req->q->queuedata;
+ struct mmc_host *host = mq->card->host;
+ enum mmc_issue_type issue_type = mmc_issue_type(mq, req);
+ bool recovery_needed = false;
+
+ switch (issue_type) {
+ case MMC_ISSUE_ASYNC:
+ case MMC_ISSUE_DCMD:
+ if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) {
+ if (recovery_needed)
+ __mmc_cqe_recovery_notifier(mq);
+ return BLK_EH_RESET_TIMER;
+ }
+ /* No timeout */
+ return BLK_EH_HANDLED;
+ default:
+ /* Timeout is handled by mmc core */
+ return BLK_EH_RESET_TIMER;
+ }
+}
+
static enum blk_eh_timer_return mmc_mq_timed_out(struct request *req,
bool reserved)
{
- return BLK_EH_RESET_TIMER;
+ struct request_queue *q = req->q;
+ struct mmc_queue *mq = q->queuedata;
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (mq->recovery_needed || !mq->use_cqe)
+ ret = BLK_EH_RESET_TIMER;
+ else
+ ret = mmc_cqe_timed_out(req);
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return ret;
+}
+
+static void mmc_mq_recovery_handler(struct work_struct *work)
+{
+ struct mmc_queue *mq = container_of(work, struct mmc_queue,
+ recovery_work);
+ struct request_queue *q = mq->queue;
+
+ mmc_get_card(mq->card, &mq->ctx);
+
+ mq->in_recovery = true;
+
+ mmc_blk_cqe_recovery(mq);
+
+ mq->in_recovery = false;
+
+ spin_lock_irq(q->queue_lock);
+ mq->recovery_needed = false;
+ spin_unlock_irq(q->queue_lock);
+
+ mmc_put_card(mq->card, &mq->ctx);
+
+ blk_mq_run_hw_queues(q, true);
}

static int mmc_queue_thread(void *d)
@@ -219,9 +343,10 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
struct request_queue *q = req->q;
struct mmc_queue *mq = q->queuedata;
struct mmc_card *card = mq->card;
+ struct mmc_host *host = card->host;
enum mmc_issue_type issue_type;
enum mmc_issued issued;
- bool get_card;
+ bool get_card, cqe_retune_ok;
int ret;

if (mmc_card_removed(mq->card)) {
@@ -233,7 +358,19 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,

spin_lock_irq(q->queue_lock);

+ if (mq->recovery_needed) {
+ spin_unlock_irq(q->queue_lock);
+ return BLK_STS_RESOURCE;
+ }
+
switch (issue_type) {
+ case MMC_ISSUE_DCMD:
+ if (mmc_cqe_dcmd_busy(mq)) {
+ mq->cqe_busy |= MMC_CQE_DCMD_BUSY;
+ spin_unlock_irq(q->queue_lock);
+ return BLK_STS_RESOURCE;
+ }
+ break;
case MMC_ISSUE_ASYNC:
break;
default:
@@ -250,6 +387,7 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,

mq->in_flight[issue_type] += 1;
get_card = (mmc_tot_in_flight(mq) == 1);
+ cqe_retune_ok = (mmc_cqe_qcnt(mq) == 1);

spin_unlock_irq(q->queue_lock);

@@ -261,6 +399,11 @@ static blk_status_t mmc_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
if (get_card)
mmc_get_card(card, &mq->ctx);

+ if (mq->use_cqe) {
+ host->retune_now = host->need_retune && cqe_retune_ok &&
+ !host->hold_retune;
+ }
+
blk_mq_start_request(req);

issued = mmc_blk_mq_issue_rq(mq, req);
@@ -322,6 +465,7 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
/* Initialize thread_sem even if it is not used */
sema_init(&mq->thread_sem, 1);

+ INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
INIT_WORK(&mq->complete_work, mmc_blk_mq_complete_work);

mutex_init(&mq->complete_lock);
@@ -370,10 +514,14 @@ static int mmc_mq_init_queue(struct mmc_queue *mq, int q_depth,
static int mmc_mq_init(struct mmc_queue *mq, struct mmc_card *card,
spinlock_t *lock)
{
+ struct mmc_host *host = card->host;
int q_depth;
int ret;

- q_depth = MMC_QUEUE_DEPTH;
+ if (mq->use_cqe)
+ q_depth = min_t(int, card->ext_csd.cmdq_depth, host->cqe_qdepth);
+ else
+ q_depth = MMC_QUEUE_DEPTH;

ret = mmc_mq_init_queue(mq, q_depth, &mmc_mq_ops, lock);
if (ret)
@@ -403,7 +551,9 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,

mq->card = card;

- if (mmc_host_use_blk_mq(host))
+ mq->use_cqe = host->cqe_enabled;
+
+ if (mq->use_cqe || mmc_host_use_blk_mq(host))
return mmc_mq_init(mq, card, lock);

mq->queue = blk_alloc_queue(GFP_KERNEL);
diff --git a/drivers/mmc/core/queue.h b/drivers/mmc/core/queue.h
index ce9249852f26..1d7d3b0afff8 100644
--- a/drivers/mmc/core/queue.h
+++ b/drivers/mmc/core/queue.h
@@ -17,6 +17,7 @@ enum mmc_issued {

enum mmc_issue_type {
MMC_ISSUE_SYNC,
+ MMC_ISSUE_DCMD,
MMC_ISSUE_ASYNC,
MMC_ISSUE_MAX,
};
@@ -92,8 +93,15 @@ struct mmc_queue {
int qcnt;

int in_flight[MMC_ISSUE_MAX];
+ unsigned int cqe_busy;
+#define MMC_CQE_DCMD_BUSY BIT(0)
+#define MMC_CQE_QUEUE_FULL BIT(1)
+ bool use_cqe;
+ bool recovery_needed;
+ bool in_recovery;
bool rw_wait;
bool waiting;
+ struct work_struct recovery_work;
wait_queue_head_t wait;
struct request *complete_req;
struct mutex complete_lock;
@@ -108,11 +116,21 @@ extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t *,
extern unsigned int mmc_queue_map_sg(struct mmc_queue *,
struct mmc_queue_req *);

+void mmc_cqe_check_busy(struct mmc_queue *mq);
+void mmc_cqe_recovery_notifier(struct mmc_request *mrq);
+
enum mmc_issue_type mmc_issue_type(struct mmc_queue *mq, struct request *req);

static inline int mmc_tot_in_flight(struct mmc_queue *mq)
{
return mq->in_flight[MMC_ISSUE_SYNC] +
+ mq->in_flight[MMC_ISSUE_DCMD] +
+ mq->in_flight[MMC_ISSUE_ASYNC];
+}
+
+static inline int mmc_cqe_qcnt(struct mmc_queue *mq)
+{
+ return mq->in_flight[MMC_ISSUE_DCMD] +
mq->in_flight[MMC_ISSUE_ASYNC];
}

--
1.9.1