> 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...
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.
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);
