[alsa-devel] USB transfer_buffer allocations on 64bit systems
oliver at neukum.org
Thu Apr 8 23:24:31 CEST 2010
Am Donnerstag, 8. April 2010 18:59:38 schrieb Alan Stern:
> On Thu, 8 Apr 2010, Oliver Neukum wrote:
> > Am Mittwoch, 7. April 2010 17:46:17 schrieb Alan Stern:
> > > Or alternatively, instead of allocating regular memory the routine
> > > could simply fail. Then the caller would be responsible for checking
> > > and using regular memory instead of dma-consistent memory. Of course,
> > > that would put an even larger burden on the caller than just forcing it
> > > to keep track of what flag to use.
> > Then it would be sensible to pass it a filled URB, modify it or return
> > an error code.
> That would work, but it doesn't match the way existing drivers use the
> interface. For example, the audio driver allocates a 16-byte coherent
> buffer and then uses four bytes from it for each of four different
That will not work with any fallback that does not yield a coherent buffer.
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