diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index df8f3612107f..0578ff253c47 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -198,6 +198,7 @@ struct nvme_queue { u32 q_depth; u16 cq_vector; u16 sq_tail; + u16 last_sq_tail; u16 cq_head; u16 qid; u8 cq_phase; @@ -455,11 +456,24 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set) return 0; } -static inline void nvme_write_sq_db(struct nvme_queue *nvmeq) +/* + * Write sq tail if we are asked to, or if the next command would wrap. + */ +static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq) { + if (!write_sq) { + u16 next_tail = nvmeq->sq_tail + 1; + + if (next_tail == nvmeq->q_depth) + next_tail = 0; + if (next_tail != nvmeq->last_sq_tail) + return; + } + if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail, nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei)) writel(nvmeq->sq_tail, nvmeq->q_db); + nvmeq->last_sq_tail = nvmeq->sq_tail; } /** @@ -476,8 +490,7 @@ static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd, cmd, sizeof(*cmd)); if (++nvmeq->sq_tail == nvmeq->q_depth) nvmeq->sq_tail = 0; - if (write_sq) - nvme_write_sq_db(nvmeq); + nvme_write_sq_db(nvmeq, write_sq); spin_unlock(&nvmeq->sq_lock); } @@ -486,7 +499,8 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx) struct nvme_queue *nvmeq = hctx->driver_data; spin_lock(&nvmeq->sq_lock); - nvme_write_sq_db(nvmeq); + if (nvmeq->sq_tail != nvmeq->last_sq_tail) + nvme_write_sq_db(nvmeq, true); spin_unlock(&nvmeq->sq_lock); } @@ -1496,6 +1510,7 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid) struct nvme_dev *dev = nvmeq->dev; nvmeq->sq_tail = 0; + nvmeq->last_sq_tail = 0; nvmeq->cq_head = 0; nvmeq->cq_phase = 1; nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];