At Fri, 03 Aug 2007 21:50:36 +0800, Songmao Tian wrote: > > Atsushi Nemoto wrote: > > On Wed, 01 Aug 2007 15:56:48 +0800, Songmao Tian <tiansm@xxxxxxxxxx> wrote: > > > >> The problem is clear: > >> 1. dma_alloc_noncoherent() return a non-cached address, and > >> virt_to_page() need a cached logical addr (Have I named it right?) > >> 2. mmaped dam buffer should be non-cached. > >> > >> We have a ugly patch, but we want to solve the problem cleanly, so can > >> anyone show me the way? > >> > > > > virt_to_page() is used in many place in mm so making it robust might > > affect performance. IMHO virt_to_page() seems too low-level as DMA > > API. > > > > If something like dma_virt_to_page(dev, cpu_addr) which can take a cpu > > address returned by dma_xxx APIs was defined, MIPS can implement it > > appropriately. > > > > And then pgprot_noncached issues still exist... > > > > --- > > Atsushi Nemoto > > > > > > > > > > I agree, and I am investigating to implement a dma_map_coherent, but It > seems dma_map_coherent doesn't solve all the problem and will change a > lot of code:( It won't be that much. You'll need to change snd_pcm_default_mmap() in sound/core/pcm_native.c to call dma_mmap_coherent() directly instead of nopage ops. But, this won't work with SG-buffers, which requires some more additional works. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
