NVMe: use split lo_hi_{read,write}q

Some controllers may require ordered split transfers even on 64bit
machines, e.g. Apple's NVMe controller as found in the MacBook8,1 and
MacBookAir7,1 (256/512GB models).

This patch enforces ordered split transfers on 64bit platforms, which
works around that issue for all controllers. As pointed out by Christoph
[1] there should be no performance impact due to that modification.

[1] http://lists.infradead.org/pipermail/linux-nvme/2015-November/002965.html

Signed-off-by: Stephan Guenther <guenther@tum.de>
Signed-off-by: Maurice Leclaire <leclaire@in.tum.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Updated by me to explicitly use lo_hi_read/writeq instead of playing
define tricks.

Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index cb89789..3435d79 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1725,7 +1725,7 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
 {
        int result;
        u32 aqa;
-       u64 cap = readq(&dev->bar->cap);
+       u64 cap = lo_hi_readq(&dev->bar->cap);
        struct nvme_queue *nvmeq;
        unsigned page_shift = PAGE_SHIFT;
        unsigned dev_page_min = NVME_CAP_MPSMIN(cap) + 12;
@@ -1774,8 +1774,8 @@ static int nvme_configure_admin_queue(struct nvme_dev *dev)
        dev->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
 
        writel(aqa, &dev->bar->aqa);
-       writeq(nvmeq->sq_dma_addr, &dev->bar->asq);
-       writeq(nvmeq->cq_dma_addr, &dev->bar->acq);
+       lo_hi_writeq(nvmeq->sq_dma_addr, &dev->bar->asq);
+       lo_hi_writeq(nvmeq->cq_dma_addr, &dev->bar->acq);
 
        result = nvme_enable_ctrl(dev, cap);
        if (result)
@@ -2606,7 +2606,7 @@ static int nvme_dev_add(struct nvme_dev *dev)
        struct pci_dev *pdev = to_pci_dev(dev->dev);
        int res;
        struct nvme_id_ctrl *ctrl;
-       int shift = NVME_CAP_MPSMIN(readq(&dev->bar->cap)) + 12;
+       int shift = NVME_CAP_MPSMIN(lo_hi_readq(&dev->bar->cap)) + 12;
 
        res = nvme_identify_ctrl(dev, &ctrl);
        if (res) {
@@ -2697,7 +2697,7 @@ static int nvme_dev_map(struct nvme_dev *dev)
                        goto unmap;
        }
 
-       cap = readq(&dev->bar->cap);
+       cap = lo_hi_readq(&dev->bar->cap);
        dev->q_depth = min_t(int, NVME_CAP_MQES(cap) + 1, NVME_Q_DEPTH);
        dev->db_stride = 1 << NVME_CAP_STRIDE(cap);
        dev->dbs = ((void __iomem *)dev->bar) + 4096;
@@ -2760,7 +2760,7 @@ static void nvme_wait_dq(struct nvme_delq_ctx *dq, struct nvme_dev *dev)
                         * queues than admin tags.
                         */
                        set_current_state(TASK_RUNNING);
-                       nvme_disable_ctrl(dev, readq(&dev->bar->cap));
+                       nvme_disable_ctrl(dev, lo_hi_readq(&dev->bar->cap));
                        nvme_clear_queue(dev->queues[0]);
                        flush_kthread_worker(dq->worker);
                        nvme_disable_queue(dev, 0);