Hello,
On 2014-09-24 19:06, Will Deacon wrote:
Hi Marek,
On Tue, Sep 16, 2014 at 12:54:28PM +0100, Marek Szyprowski wrote:
If device has no max_seg_size set, we assume that there is no limit and
force it to DMA_BIT_MASK(32) to always use contiguous mappings in DMA
address space.
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
arch/arm/mm/dma-mapping.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index bcd5f836f27e..84705e24571b 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2050,6 +2050,22 @@ int arm_iommu_attach_device(struct device *dev,
{
int err;
+ /*
+ * if device has no max_seg_size set, we assume that there is no limit
+ * and force it to DMA_BIT_MASK(32) to always use contiguous mappings
+ * in DMA address space
+ */
+ if (!dev->dma_parms) {
+ dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL);
+ if (!dev->dma_parms)
+ return -ENOMEM;
+ }
+ if (!dev->dma_parms->max_segment_size) {
+ err = dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
Would it make more sense to base this default value off the dma_mask?
In my IOMMU series, of_dma_configure passes back a size parameter to
arch_setup_dma_ops which is calculated from the dma-ranges property or the
coherent dma mask if the ranges property is absent, so maybe we should set
this there too?
Right, good idea. This patch predates your arch_setup_dma_ops changes, so I
had to use something. The value taken from dma_mask is much better than
hardcoded
DMA_BIT_MASK(32). Do you want to include an updated patch in next
version of your
arch_setup_dma_ops patchset?
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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