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...:) 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
