2 files changed, 15 insertions, 3 deletions

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index cfe5932821d8..a17f80fa3881 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -70,6 +70,7 @@ struct nvme_dev {
         struct dma_pool *prp_small_pool;
         int instance;
         int queue_count;
+        int db_stride;
         u32 ctrl_config;
         struct msix_entry *entry;
         struct nvme_bar __iomem *bar;
@@ -672,7 +673,7 @@ static irqreturn_t nvme_process_cq(struct nvme_queue *nvmeq)
         if (head == nvmeq->cq_head && phase == nvmeq->cq_phase)
                 return IRQ_NONE;
 
-        writel(head, nvmeq->q_db + 1);
+        writel(head, nvmeq->q_db + (1 << nvmeq->dev->db_stride));
         nvmeq->cq_head = head;
         nvmeq->cq_phase = phase;
 
@@ -889,7 +890,7 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid,
         init_waitqueue_head(&nvmeq->sq_full);
         init_waitqueue_entry(&nvmeq->sq_cong_wait, nvme_thread);
         bio_list_init(&nvmeq->sq_cong);
-        nvmeq->q_db = &dev->dbs[qid * 2];
+        nvmeq->q_db = &dev->dbs[qid << (dev->db_stride + 1)];
         nvmeq->q_depth = depth;
         nvmeq->cq_vector = vector;
 
@@ -981,6 +982,7 @@ static int __devinit nvme_configure_admin_queue(struct nvme_dev *dev)
 
         cap = readq(&dev->bar->cap);
         timeout = ((NVME_CAP_TIMEOUT(cap) + 1) * HZ / 2) + jiffies;
+        dev->db_stride = NVME_CAP_STRIDE(cap);
 
         while (!(readl(&dev->bar->csts) & NVME_CSTS_RDY)) {
                 msleep(100);
@@ -1357,7 +1359,7 @@ static int set_queue_count(struct nvme_dev *dev, int count)
 
 static int __devinit nvme_setup_io_queues(struct nvme_dev *dev)
 {
-        int result, cpu, i, nr_io_queues;
+        int result, cpu, i, nr_io_queues, db_bar_size;
 
         nr_io_queues = num_online_cpus();
         result = set_queue_count(dev, nr_io_queues);
@@ -1369,6 +1371,15 @@ static int __devinit nvme_setup_io_queues(struct nvme_dev *dev)
         /* Deregister the admin queue's interrupt */
         free_irq(dev->entry[0].vector, dev->queues[0]);
 
+        db_bar_size = 4096 + ((nr_io_queues + 1) << (dev->db_stride + 3));
+        if (db_bar_size > 8192) {
+                iounmap(dev->bar);
+                dev->bar = ioremap(pci_resource_start(dev->pci_dev, 0),
+                                                                db_bar_size);
+                dev->dbs = ((void __iomem *)dev->bar) + 4096;
+                dev->queues[0]->q_db = dev->dbs;
+        }
+
         for (i = 0; i < nr_io_queues; i++)
                 dev->entry[i].entry = i;
         for (;;) {
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index c96ab0f5ef6f..2a2c535c8345 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -36,6 +36,7 @@ struct nvme_bar {
 };
 
 #define NVME_CAP_TIMEOUT(cap)   (((cap) >> 24) & 0xff)
+#define NVME_CAP_STRIDE(cap)    (((cap) >> 32) & 0xf)
 
 enum {
         NVME_CC_ENABLE          = 1 << 0,