From 7547881d0951384f9833ec3a80fac8f3f16f3b98 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 16 Feb 2011 09:59:59 -0500 Subject: [PATCH] NVMe: Correct SQ doorbell semantics The value written to the doorbell needs to be the first free index in the queue, not the most recently used index in the queue. Signed-off-by: Matthew Wilcox --- drivers/block/nvme.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c index df1d8bda8c7c..af45e286d5dd 100644 --- a/drivers/block/nvme.c +++ b/drivers/block/nvme.c @@ -246,9 +246,9 @@ static int nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd) spin_lock_irqsave(&nvmeq->q_lock, flags); tail = nvmeq->sq_tail; memcpy(&nvmeq->sq_cmds[tail], cmd, sizeof(*cmd)); - writel(tail, nvmeq->q_db); if (++tail == nvmeq->q_depth) tail = 0; + writel(tail, nvmeq->q_db); nvmeq->sq_tail = tail; spin_unlock_irqrestore(&nvmeq->q_lock, flags); @@ -471,9 +471,9 @@ static int nvme_submit_bio_queue(struct nvme_queue *nvmeq, struct nvme_ns *ns, cmnd->rw.control = cpu_to_le16(control); cmnd->rw.dsmgmt = cpu_to_le32(dsmgmt); - writel(nvmeq->sq_tail, nvmeq->q_db); if (++nvmeq->sq_tail == nvmeq->q_depth) nvmeq->sq_tail = 0; + writel(nvmeq->sq_tail, nvmeq->q_db); return 0; -- 2.20.1