Hi Santosh, On Friday 14 March 2014 12:15:11 Santosh Shilimkar wrote: > + Russell, Arnd > > On Thursday 13 March 2014 10:47 PM, Anna, Suman wrote: > > On 03/07/2014 06:46 PM, Laurent Pinchart wrote: > >> The page table entries must be cleaned from the cache before being > >> accessed by the IOMMU. Instead of implementing cache management manually > >> (and ignoring L2 cache), use clean_dcache_area() to make sure the > >> entries are visible to the device. > > > > Thanks for fixing this, this has been long pending. There have been some > > previous attempts at this as well by Ramesh Gupta, with the last thread > > (a long time now) being > > http://marc.info/?t=134752035400001&r=1&w=2 > > > > Santosh, > > Can you please take a look at this patch and provide your comments? > > > > regards > > Suman > > > >> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > >> --- > >> > >> drivers/iommu/omap-iommu.c | 41 ++++++++++----------------------------- > >> 1 file changed, 10 insertions(+), 31 deletions(-) > >> > >> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c > >> index a893eca..bb605c9 100644 > >> --- a/drivers/iommu/omap-iommu.c > >> +++ b/drivers/iommu/omap-iommu.c > >> @@ -500,24 +500,9 @@ EXPORT_SYMBOL_GPL(omap_foreach_iommu_device); > >> /* > >> * H/W pagetable operations > >> */ > >> -static void flush_iopgd_range(u32 *first, u32 *last) > >> +static void flush_pgtable(void *addr, size_t size) > >> { > >> - /* FIXME: L2 cache should be taken care of if it exists */ > >> - do { > >> - asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pgd" > >> - : : "r" (first)); > >> - first += L1_CACHE_BYTES / sizeof(*first); > >> - } while (first <= last); > >> -} > >> - > >> -static void flush_iopte_range(u32 *first, u32 *last) > >> -{ > >> - /* FIXME: L2 cache should be taken care of if it exists */ > >> - do { > >> - asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pte" > >> - : : "r" (first)); > >> - first += L1_CACHE_BYTES / sizeof(*first); > >> - } while (first <= last); > >> + clean_dcache_area(addr, size); > > I remember NAKing this approach in past and my stand remains same. > The cache APIs which you are trying to use here are not suppose > to be used outside. Please note that the omap-iommu driver already uses clean_dcache_area(). That's where I got the idea :-) > I think the right way to fix this is to make use of streaming APIs. > If needed, IOMMU can have its own dma_ops for special case > handling if any. I can replace clean_dcache_area() with dma_map_page() as done by the arm-smmu driver. If that's fine I'll modify this patch accordingly in v2. > Russell, Arnd might have more ideas. > > >> } > >> > >> static void iopte_free(u32 *iopte) -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
