On Sun, Apr 15, 2007 at 11:26:05PM +0800, tiansm@lemote.com wrote:

(Adding a few more people to the cc'list)

sound/core/pcm_native.c | 10 ++++++++++ sound/core/sgbuf.c | 9 +++++++++ 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 3e276fc..9005bac 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -3145,7 +3145,11 @@ 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)

Please use CONFIG_MIPS instead of __mips__ in #if / #ifdefs.

The question if #ifdefing is the right approach to solve this problem is something else but I think no, ....

• page = virt_to_page(CAC_ADDR(vaddr));
  

+#else page = virt_to_page(vaddr); +#endif

So this is needed because the MIPS virt_to_page is returning a unsuitable value if vaddress is not a KSEG0 (64-bit: cached XKPHYS) address which is what GFP allocations and the slab will return. So now we have to deciede if

a) the MIPS __pa() should be changed to handle uncached addresses. b) the sound code here is simply broken.

Some drivers seem to allocate runtime->dma_area from vmalloc, so this whole area in the sound code is looking like built on quicksand ...

} get_page(page); if (type) @@ -3261,6 +3265,12 @@ 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);
• area->vm_flags |= ( VM_RESERVED | VM_IO);

VM_RESERVED will prevent the buffer from being freed. I assume that is another workaround for some kernel subsystem blowing up when being fed a pointer to an uncached RAM address? This smells like a memory leak.

+#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..535f0bc 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));
  

VM_RESERVED will prevent the buffer from being freed. I assume that is another workaround for some kernel subsystem blowing up when being fed a pointer to an uncached RAM address? This smells like a memory leak.

+#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 | VM_IO, pgprot_noncached(PAGE_KERNEL));

+#else dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL); +#endif

I would suggest to get rid of this ifdef with a new arch-specific function like vmap_io_buffer which will do whatever a platform seems fit for this case?

if (! dmab->area) goto _failed; return dmab->area;

Ralf