[PATCH 1/2] Add support for 32 bit DMA for 32 bit machines

[Chayan Biswas]

We set the DMA mask to 32 bit if the system is a 32 bit system. We also
try to set to 32 bit DMA if setting the 64 bit DMA fails, and clean up
if both fails.

Signed-off-by: Chayan Biswas <Chayan.Biswas at sandisk.com>
---
 drivers/block/nvme.c |   19 +++++++++++++++++--
 1 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index 993c014..4b706b5 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -42,6 +42,7 @@

 #include <asm-generic/io-64-nonatomic-lo-hi.h>

+#define IS_DMA64               (sizeof(dma_addr_t) == 8)
 #define NVME_Q_DEPTH 1024
 #define SQ_SIZE(depth)         (depth * sizeof(struct nvme_command))
 #define CQ_SIZE(depth)         (depth * sizeof(struct nvme_completion))
@@ -1662,8 +1663,21 @@ static int __devinit nvme_probe(struct pci_dev *pdev,
        INIT_LIST_HEAD(&dev->namespaces);
        dev->pci_dev = pdev;
        pci_set_drvdata(pdev, dev);
-       dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
-       dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
+       if (IS_DMA64) {
+               if (dma_set_mask(&pdev->dev, DMA_BIT_MASK(64)) != 0) {
+                       if (dma_set_mask(&pdev->dev, DMA_BIT_MASK(32)) != 0)
+                               goto fail_set_dma_mask;
+
+                       dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+               } else {
+                       dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
+               }
+       } else {
+               if (dma_set_mask(&pdev->dev, DMA_BIT_MASK(32)) != 0)
+                       goto fail_set_dma_mask;
+
+               dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+       }
        result = nvme_set_instance(dev);
        if (result)
                goto disable;
@@ -1705,6 +1719,7 @@ static int __devinit nvme_probe(struct pci_dev *pdev,
        iounmap(dev->bar);
  disable_msix:
        pci_disable_msix(pdev);
+ fail_set_dma_mask:
        nvme_release_instance(dev);
        nvme_release_prp_pools(dev);
  disable:
--
1.7.1


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