On Mon, Jul 27, 2015 at 02:23:26PM +0100, Robin Murphy wrote: > On 16/07/15 10:04, Yong Wu wrote: > >This patch adds support for mediatek m4u (MultiMedia Memory Management > >Unit). > > > >Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx> > [...] > >+static void mtk_iommu_flush_pgtable(void *ptr, size_t size, void *cookie) > >+{ > >+ struct mtk_iommu_domain *domain = cookie; > >+ unsigned long offset = (unsigned long)ptr & ~PAGE_MASK; > >+ > >+ dma_map_page(domain->data->dev, virt_to_page(ptr), offset, > >+ size, DMA_TO_DEVICE); > > Nit: this looks like it may as well be dma_map_single. > > It would probably be worth following it with a matching unmap too, just to > avoid any possible leakage bugs (especially if this M4U ever appears in a > SoC supporting RAM above the 32-bit boundary). Why not do the job properly? Take a look at how I implemented the streaming DMA API on Tegra SMMU (patch set recently sent out earlier today). There's no need for hacks like dma_map_page() (and discarding it's return value) or dma_map_page() followed by dma_unmap_page(). -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html