On Thu, Jan 05, 2012 at 03:29:30PM +0100, Hiroshi Doyu wrote: > Ok, the above function order should be as below? > > page = alloc_page(GFP_KERNEL); > cpu_addr = kmap(page); > memset(cpu_addr, 0xa5, PAGE_SIZE); > dma_addr = dma_map_page(dev, page, 0, PAGE_SIZE, DMA_TO_DEVICE); > < expect GPU does something > > dma_unmap_page(dev, dma_addr, PAGE_SIZE, DMA_TO_DEVICE); > < CPU can access data here again> > kunmap(cpu_addr); > __free_page(page); That should work, but it's not particularly nice to wrap kmap around the DMA API. Bear in mind that alloc_page(GFP_KERNEL) will always give you a lowmem page. So, you might as well do: page = alloc_page(GFP_KERNEL); cpu_addr = page_address(page); memset() dma_addr = dma_map_single(dev, cpu_addr, PAGE_SIZE, DMA_TO_DEVICE); < GPU access > dma_unmap_single(dev, dma_ddr, PAGE_SIZE, DMA_TO_DEVICE); < CPU access > __free_page(page); and this doesn't raise any issues with kmap vs DMA API. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
