Hello,
On Wednesday, March 07, 2012 12:22 AM Russell King - ARM Linux wrote:
On Wed, Feb 29, 2012 at 04:04:22PM +0100, Marek Szyprowski wrote:
+static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,struct dma_attrs *attrs)+{
- struct arm_vmregion *c;
- vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
- c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
What protects this against other insertions/removals from the list?
arm_vmregion_* functions have their own spinlock.
(snipped)
- if (c) {
struct page **pages = c->priv;__dma_free_remap(cpu_addr, size);__iommu_remove_mapping(dev, handle, size);__iommu_free_buffer(dev, pages, size);- }
+}
+/*
- Map a part of the scatter-gather list into contiguous io address space
- */
+static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
size_t size, dma_addr_t *handle,enum dma_data_direction dir)+{
- struct dma_iommu_mapping *mapping = dev->archdata.mapping;
- dma_addr_t iova, iova_base;
- int ret = 0;
- unsigned int count;
- struct scatterlist *s;
- size = PAGE_ALIGN(size);
- *handle = ARM_DMA_ERROR;
- iova_base = iova = __alloc_iova(mapping, size);
- if (iova == ARM_DMA_ERROR)
return -ENOMEM;- for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s))
- {
phys_addr_t phys = page_to_phys(sg_page(s));unsigned int len = PAGE_ALIGN(s->offset + s->length);if (!arch_is_coherent())__dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);ret = iommu_map(mapping->domain, iova, phys, len, 0);Dealing with phys addresses on one part and pages + offset + length in a different part doesn't look like a good idea. Why can't there be some consistency?
Well, I have no idea how to be more consistent here. scatter-lists operates on pages + offsets + length parameters. iommu api operates on the whole pages, but they are referred with physical address. Right now I cannot change any of it, at least not it the near future.
Best regards