On Thu, 24 Oct 2013, Stefano Stabellini wrote: > On Wed, 23 Oct 2013, Konrad Rzeszutek Wilk wrote: > > On Wed, Oct 23, 2013 at 06:20:25PM +0100, Stefano Stabellini wrote: > > > On Wed, 23 Oct 2013, Konrad Rzeszutek Wilk wrote: > > > > On Thu, Oct 17, 2013 at 06:43:28PM +0100, Stefano Stabellini wrote: > > > > > Call xen_dma_map_page, xen_dma_unmap_page, > > > > > xen_dma_sync_single_for_cpu, > > > > > xen_dma_sync_single_for_device from swiotlb-xen to ensure cpu/device > > > > > coherency of the pages used for DMA, including the ones belonging to > > > > > the > > > > > swiotlb buffer. > > > > > > > > You lost me. > > > > > > > > Isn't it the driver's responsibility to do this? > > > > > > > > Looking at what 'xen_dma_map_page()' does for x86 it looks to add an > > > > extra > > > > call - page_to_phys - and we ignore it here. > > > > > > map_page on arm calls the right cache flushes needed to communicate with > > > the device. Same with unmap_page. > > > > If this is flushing the cache then I think it makes more sense to do > > that without this fancy 'dma_map_page'. > > > > Just call it 'xen_flush_dma_page' and make it a nop on all platforms > > except ARM. > > I am OK with making it a nop on x86, it makes sense. > However I would like to keep it called xen_dma_map_page: after all it > corresponds exactly to the native map_page dma_op. It is part of the same > "contract".
for example we can turn xen_dma_map_page into a function that returns void, this way we can remove the page_to_phys on x86 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
