Hi, In http://www.linux-mips.org/archives/linux-mips/2007-04/msg00114.html, Atsushi Nemoto pointed out the problem is discussed before, the thread can be found at http://lkml.org/lkml/2006/1/25/117. Thanks Atsushi Nemoto:) 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?
Regards, Tian
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 59b29cd..fd0aa66 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3138,7 +3138,11 @@ static struct page *snd_pcm_mmap_data_nopage(struct vm_area_struct *area, return NOPAGE_OOM; /* XXX: is this really due to OOM? */ } else { vaddr = runtime->dma_area + offset; +#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT) + page = virt_to_page(CAC_ADDR(vaddr)); +#else page = virt_to_page(vaddr); +#endif } get_page(page); if (type) @@ -3254,6 +3258,11 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area) substream = pcm_file->substream; snd_assert(substream != NULL, return -ENXIO);
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT) + /* all mmap using uncached mode */ + area->vm_page_prot = pgprot_noncached(area->vm_page_prot); +#endif + offset = area->vm_pgoff << PAGE_SHIFT; switch (offset) { case SNDRV_PCM_MMAP_OFFSET_STATUS: diff --git a/sound/core/sgbuf.c b/sound/core/sgbuf.c index cefd228..2251e70 100644 --- a/sound/core/sgbuf.c +++ b/sound/core/sgbuf.c @@ -91,12 +91,21 @@ void *snd_malloc_sgbuf_pages(struct device *device, } sgbuf->table[i].buf = tmpb.area; sgbuf->table[i].addr = tmpb.addr; +#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT) + sgbuf->page_table[i] = virt_to_page(CAC_ADDR(tmpb.area)); +#else sgbuf->page_table[i] = virt_to_page(tmpb.area); +#endif sgbuf->pages++; }
sgbuf->size = size; +#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT) + /* maybe we should use uncached accelerated mode */ + dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, pgprot_noncached(PAGE_KERNEL)); +#else dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL); +#endif if (! dmab->area) goto _failed; return dmab->area;