At Fri, 15 Jan 2010 14:28:02 +1100,
Benjamin Herrenschmidt wrote:
>
>
> > A quick patch below (totally untested!) might do that.
> > It's passing the device struct blindly, so not sure whether this would
> > actually work for all dma_alloc_coherent().
>
> On archs that have dma_ops such as powerpc (but I think x86 too
> nowadays) you cannot use the USB device for dma_* operations. You need
> to get up to the host controller device...
Yep, I don't think this being a proper fix, too.
> It -might- be worth looking at adding code to the USB stack to propagate
> the parent device dma_ops down to USB devices... hard to tell.
Or we may simply need to drop the mmap support on such architectures...
thanks,
Takashi
>
> Cheers,
> Ben.
>
> >
> > Takashi
> >
> > ---
> > diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
> > index 9edef46..6c82026 100644
> > --- a/sound/usb/usbaudio.c
> > +++ b/sound/usb/usbaudio.c
> > @@ -734,7 +734,7 @@ static void snd_complete_sync_urb(struct urb *urb)
> > }
> > }
> >
> > -
> > +#ifdef USBAUDIO_VMALLOC_BUFFER
> > /* get the physical page pointer at the given offset */
> > static struct page *snd_pcm_get_vmalloc_page(struct snd_pcm_substream *subs,
> > unsigned long offset)
> > @@ -769,6 +769,24 @@ static int snd_pcm_free_vmalloc_buffer(struct snd_pcm_substream *subs)
> > return 0;
> > }
> >
> > +#define preallocate_buffer(chip, pcm, stream) /* NOP */
> > +
> > +#else
> > +#define snd_pcm_get_vmalloc_page NULL
> > +#define snd_pcm_alloc_vmalloc_buffer snd_pcm_lib_malloc_pages
> > +#define snd_pcm_free_vmalloc_buffer snd_pcm_lib_free_pages
> > +
> > +static int preallocate_buffer(struct snd_usb_audio *chip, struct snd_pcm *pcm,
> > + int stream)
> > +{
> > + struct snd_pcm_substream *subs = pcm->streams[stream].substream;
> > + if (!subs)
> > + return 0;
> > + return snd_pcm_lib_preallocate_pages(subs, SNDRV_DMA_TYPE_DEV,
> > + chip->card->dev,
> > + 1024 * 64, 1024 * 1024);
> > +}
> > +#endif
> >
> > /*
> > * unlink active urbs.
> > @@ -2328,6 +2346,7 @@ static int add_audio_endpoint(struct snd_usb_audio *chip, int stream, struct aud
> > err = snd_pcm_new_stream(as->pcm, stream, 1);
> > if (err < 0)
> > return err;
> > + preallocate_buffer(chip, as->pcm, stream);
> > init_substream(as, stream, fp);
> > return 0;
> > }
> > @@ -2356,6 +2375,7 @@ static int add_audio_endpoint(struct snd_usb_audio *chip, int stream, struct aud
> > else
> > strcpy(pcm->name, "USB Audio");
> >
> > + preallocate_buffer(chip, pcm, stream);
> > init_substream(as, stream, fp);
> >
> > list_add(&as->list, &chip->pcm_list);
>
>
