On Wed, Oct 07, 2020 at 02:21:43PM +0200, Tomasz Figa wrote: > My initial feeling is that it should work, but we'll give you a > definitive answer once we prototype it. :) > > We might actually give it a try in the USB HCD subsystem as well, to > implement usb_alloc_noncoherent(), as an optimization for drivers > which have to perform multiple random accesses to the URB buffers. I > think you might recall discussing this by the way of the pwc and > uvcvideo camera drivers.
Yes. I guess for usb the dma_alloc_noncoherent as-is in linux-next might be better. So if you have the cycles please prototype it either way, although for that we'd also need at least a mmap_noncoherent method, and probaby a get_sgtable_noncoherent one.
