Messages in this thread Patch in this message | | | Date | Wed, 18 Apr 2007 14:54:12 +0100 | From | Ralf Baechle <> | Subject | Re: [PATCH 16/16] alsa sound support for mips |
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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;
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