Merge branch 'for-linus-dma-masks' of git://git.linaro.org/people/rmk/linux-arm

[cascardo/linux.git] / arch / arm / mm / dma-mapping.c

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 1272ed2..644d91f 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -159,7 +159,7 @@ EXPORT_SYMBOL(arm_coherent_dma_ops);
 
 static u64 get_coherent_dma_mask(struct device *dev)
 {
-       u64 mask = (u64)arm_dma_limit;
+       u64 mask = (u64)DMA_BIT_MASK(32);
 
        if (dev) {
                mask = dev->coherent_dma_mask;
@@ -173,10 +173,30 @@ static u64 get_coherent_dma_mask(struct device *dev)
                        return 0;
                }
 
-               if ((~mask) & (u64)arm_dma_limit) {
-                       dev_warn(dev, "coherent DMA mask %#llx is smaller "
-                                "than system GFP_DMA mask %#llx\n",
-                                mask, (u64)arm_dma_limit);
+               /*
+                * If the mask allows for more memory than we can address,
+                * and we actually have that much memory, then fail the
+                * allocation.
+                */
+               if (sizeof(mask) != sizeof(dma_addr_t) &&
+                   mask > (dma_addr_t)~0 &&
+                   dma_to_pfn(dev, ~0) > arm_dma_pfn_limit) {
+                       dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n",
+                                mask);
+                       dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n");
+                       return 0;
+               }
+
+               /*
+                * Now check that the mask, when translated to a PFN,
+                * fits within the allowable addresses which we can
+                * allocate.
+                */
+               if (dma_to_pfn(dev, mask) < arm_dma_pfn_limit) {
+                       dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",
+                                mask,
+                                dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,
+                                arm_dma_pfn_limit + 1);
                        return 0;
                }
        }
@@ -1007,8 +1027,27 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
  */
 int dma_supported(struct device *dev, u64 mask)
 {
-       if (mask < (u64)arm_dma_limit)
+       unsigned long limit;
+
+       /*
+        * If the mask allows for more memory than we can address,
+        * and we actually have that much memory, then we must
+        * indicate that DMA to this device is not supported.
+        */
+       if (sizeof(mask) != sizeof(dma_addr_t) &&
+           mask > (dma_addr_t)~0 &&
+           dma_to_pfn(dev, ~0) > arm_dma_pfn_limit)
+               return 0;
+
+       /*
+        * Translate the device's DMA mask to a PFN limit.  This
+        * PFN number includes the page which we can DMA to.
+        */
+       limit = dma_to_pfn(dev, mask);
+
+       if (limit < arm_dma_pfn_limit)
                return 0;
+
        return 1;
 }
 EXPORT_SYMBOL(dma_supported);