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

Andi Kleen andi at firstfloor.org
Mon Apr 12 13:53:00 CEST 2010

> Which is exactly what usb_buffer_alloc() does already. So at least for
> x86 you say this is the right thing to do? However, we don't necessarily
> need coherent memory on other platforms, which is why I hessitate to
> enforce that type of memory for all transfer_buffer allocations.

Yes today it's faster at least.

Probably we should have better interfaces for this, but we don't.

> > Or just use GFP_KERNEL and pci_map_* later.
> The USB core does this already, but at least on Pedro's machine, this
> seems unsufficient. Unfortunately, I can't reproduce the issue yet, even
> with more than 4GB of RAM installed.

Then something must be broken in Pedro's system and likely other drivers
will also not work. I don't think it should be worked around in the USB layer.

ak at linux.intel.com -- Speaking for myself only.
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