On 05/14/2015 02:43 AM, Benjamin Herrenschmidt wrote:
> This patch adds the ability to the DMA direct ops to fallback to the IOMMU
> ops for coherent alloc/free if the coherent mask of the device isn't
> suitable for accessing the direct DMA space and the device also happens
> to have an active IOMMU table.
>
> Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Thanks Ben. This doesn't quite work, though, since pci_set_consistent_dma_mask
ends up calling dma_supported, which returns 0 here for a 32 bit mask if
pci_set_consistent_dma_mask was already called with a 64 bit mask. I worked
around it with the hack below and saw that I was able to get 64 bit DMA
and the card showed up all the drives. We'll need a better a better fix
for upstream obviously, but I wanted to be able to check out the rest of the patch
a bit...
Thanks,
Brian
--
Brian King
Power Linux I/O
IBM Linux Technology Center
Signed-off-by: Brian King <brking@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/dma.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff -puN arch/powerpc/kernel/dma.c~powerpc_iommu_hybrid_fixup arch/powerpc/kernel/dma.c
--- linux/arch/powerpc/kernel/dma.c~powerpc_iommu_hybrid_fixup 2015-05-14 10:28:38.361416590 -0500
+++ linux-bjking1/arch/powerpc/kernel/dma.c 2015-05-14 10:54:39.367292683 -0500
@@ -62,6 +62,16 @@ static int dma_direct_dma_supported(stru
#endif
}
+static int dma_direct_is_dma_supported(struct device *dev, u64 mask)
+{
+ if (!dma_direct_dma_supported(dev, mask)) {
+ if (mask < 0xfffffff)
+ return 0;
+ }
+
+ return 1;
+}
+
void *__dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
struct dma_attrs *attrs)
@@ -273,7 +283,7 @@ struct dma_map_ops dma_direct_ops = {
.mmap = dma_direct_mmap_coherent,
.map_sg = dma_direct_map_sg,
.unmap_sg = dma_direct_unmap_sg,
- .dma_supported = dma_direct_dma_supported,
+ .dma_supported = dma_direct_is_dma_supported,
.map_page = dma_direct_map_page,
.unmap_page = dma_direct_unmap_page,
.get_required_mask = dma_direct_get_required_mask,
_
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