[alsa-devel] USB transfer_buffer allocations on 64bit systems
stern at rowland.harvard.edu
Mon Apr 12 18:57:16 CEST 2010
On Mon, 12 Apr 2010, Andi Kleen wrote:
> On Mon, Apr 12, 2010 at 12:17:22PM -0400, Alan Stern wrote:
> > 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
> Hmm, thanks. But things must still go wrong somewhere, otherwise
> the GFP_DMA32 wouldn't be needed?
Indeed, something must go wrong somewhere. Since Daniel's patch fixed
the problem by changing the buffer from a streaming mapping to a
coherent mapping, it's logical to assume that bad DMA addresses have
something to do with it. But we don't really know for certain.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
More information about the Alsa-devel