[alsa-devel] USB transfer_buffer allocations on 64bit systems

[Alan Stern]

On Mon, 12 Apr 2010, Andi Kleen wrote:

> > Well, the sound driver itself doesn't care for any of those things, just
> > like any other USB driver doesn't. The USB core itself of the host
> > controller driver should do, and as far as I can see, it does that, yes.
> 
> Hmm, still things must go wrong somewhere. Perhaps need some instrumentation
> to see if all the transfer buffers really hit the PCI mapping functions.

Such a test has already been carried out earlier in this thread:

	http://marc.info/?l=linux-usb&m=127074587029353&w=2
	http://marc.info/?l=linux-usb&m=127076841801051&w=2
	http://marc.info/?l=linux-usb&m=127082890510415&w=2

> It might be interesting to test if the device works with enabled
> IOMMU. That would trigger any failures to properly map the buffers
> earlier.

Alan Stern