On Thu, Oct 12, 2017 at 08:31:31PM +0800, Wei Hu (Xavier) wrote: > > > On 2017/10/1 0:10, Leon Romanovsky wrote: > > On Sat, Sep 30, 2017 at 05:28:59PM +0800, Wei Hu (Xavier) wrote: > > > If the IOMMU is enabled, the length of sg obtained from > > > __iommu_map_sg_attrs is not 4kB. When the IOVA is set with the sg > > > dma address, the IOVA will not be page continuous. and the VA > > > returned from dma_alloc_coherent is a vmalloc address. However, > > > the VA obtained by the page_address is a discontinuous VA. Under > > > these circumstances, the IOVA should be calculated based on the > > > sg length, and record the VA returned from dma_alloc_coherent > > > in the struct of hem. > > > > > > Signed-off-by: Wei Hu (Xavier) <xavier.huwei@xxxxxxxxxx> > > > Signed-off-by: Shaobo Xu <xushaobo2@xxxxxxxxxx> > > > Signed-off-by: Lijun Ou <oulijun@xxxxxxxxxx> > > > --- > > Doug, > > > > I didn't invest time in reviewing it, but having "is_vmalloc_addr" in > > driver code to deal with dma_alloc_coherent is most probably wrong. > > > > Thanks > Hi, Leon & Doug > We refered the function named __ttm_dma_alloc_page in the kernel code as > below: > And there are similar methods in bch_bio_map and mem_to_page functions > in current 4.14-rcx. Let's put aside TTM, I don't know the rationale behind their implementation, but both mem_to_page and bch_bio_map are don't operate on DMA addresses and don't belong to HW driver code. Thanks
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