At Fri, 03 Aug 2007 23:57:07 +0800, Songmao Tian wrote: > > Takashi Iwai wrote: > > 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 > > > > > > > I have no idea if the patch can work, the idea is not very clear now. > And I use vt686b ac97 sound driver, the driver use sgbuf, so I will > write a test program tomorrow. Good sleep...:) Ah, that's a bad luck. Then your patch won't work as it is. We'll need another function for SG-buffer, that calls dma_mmap_coherent() for each page found in the given buffer. Takashi > And if any of you can take some time look into the patch, and give some > review will be appreciated:) > > diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c > index 76903c7..f088a6b 100644 > --- a/arch/mips/mm/dma-default.c > +++ b/arch/mips/mm/dma-default.c > @@ -369,3 +369,23 @@ void dma_cache_sync(struct device *dev, void > *vaddr, size_t size, > } > > EXPORT_SYMBOL(dma_cache_sync); > + > +static int dma_mmap(struct device *dev, struct vm_area_struct *vma, > + void *cpu_addr, dma_addr_t dma_addr, size_t size) > +{ > + if (remap_pfn_range(vma, vma->vm_start, > + PFN_DOWN(virt_to_phys(CAC_ADDR(cpu_addr))) + > vma->vm_pgoff, > + vma->vm_end - vma->vm_start, > + vma->vm_page_prot)) > + return -EAGAIN; > + return 0; > +} > + > +int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, > + void *cpu_addr, dma_addr_t dma_addr, size_t size) > +{ > + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > + return dma_mmap(dev, vma, cpu_addr, dma_addr, size); > +} > +EXPORT_SYMBOL(dma_mmap_coherent); > + > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c > index 59b29cd..af82a3b 100644 > --- a/sound/core/pcm_native.c > +++ b/sound/core/pcm_native.c > @@ -3152,6 +3152,8 @@ static struct vm_operations_struct > snd_pcm_vm_ops_data = > .close = snd_pcm_mmap_data_close, > .nopage = snd_pcm_mmap_data_nopage, > }; > +int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, > + void *cpu_addr, dma_addr_t dma_addr, size_t size); > > /* > * mmap the DMA buffer on RAM > @@ -3159,9 +3161,10 @@ static struct vm_operations_struct > snd_pcm_vm_ops_data = > static int snd_pcm_default_mmap(struct snd_pcm_substream *substream, > struct vm_area_struct *area) > { > - area->vm_ops = &snd_pcm_vm_ops_data; > + struct snd_pcm_runtime *runtime = substream->runtime; > area->vm_private_data = substream; > - area->vm_flags |= VM_RESERVED; > + dma_mmap_coherent(NULL, area, runtime->dma_area, > + runtime->dma_addr, runtime->dma_bytes); > atomic_inc(&substream->mmap_count); > return 0; > } > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel >
