nvme: temporary fix for Apple controller reset

Recent patches added basic support for the Apple NVMe controller but
still cause resets and data corruption on that particular controller
when a specific pattern of read/flush commands occurs. Limiting the
queue depth to 2 works around that issue.

This patch enforces that limit only for the Apple controller and is
considered a temporary fix until we find the root source of that
problem.

Signed-off-by: Stephan Günther <guenther@tum.de>
Signed-off-by: Maurice Leclaire <leclaire@in.tum.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index f3b53af789efccbddfedc0b37319dcaa1c264bfd..9e294ff4e652a2bb8daa9e3f4a94cc09e8bb8b88 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2708,6 +2708,18 @@ static int nvme_dev_map(struct nvme_dev *dev)
        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;
+
+       /*
+        * Temporary fix for the Apple controller found in the MacBook8,1 and
+        * some MacBook7,1 to avoid controller resets and data loss.
+        */
+       if (pdev->vendor == PCI_VENDOR_ID_APPLE && pdev->device == 0x2001) {
+               dev->q_depth = 2;
+               dev_warn(dev->dev, "detected Apple NVMe controller, set "
+                       "queue depth=%u to work around controller resets\n",
+                       dev->q_depth);
+       }
+
        if (readl(&dev->bar->vs) >= NVME_VS(1, 2))
                dev->cmb = nvme_map_cmb(dev);