Hi Christoph, On Wed, May 01, 2019 at 07:29:12PM +0200, Christoph Hellwig wrote: > On Wed, May 01, 2019 at 05:18:59PM +0000, Paul Burton wrote: > > I'm not so sure about this part though. > > > > On MIPS we currently don't clear the allocated memory with memset. Is > > doing that really necessary? > > We are clearling it on mips, it is inside dma_direct_alloc_pages. Ah, of course, I clearly require more caffeine :) > > If it is necessary then as-is this code will clear the allocated memory > > using uncached writes which will be pretty slow. It would be much more > > efficient to perform the memset before arch_dma_prep_coherent() & before > > converting ret to an uncached address. > > Yes, we could do that. Great; using cached writes would match the existing MIPS behavior. Thanks, Paul