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Harald Welte laforge at gnumonks.orgHi Peter and others,
On Sat, Feb 18, 2012 at 08:18:33PM +0100, Peter Stuge wrote:
> I note that all data to be transmitted is copied byte for byte from
> the rctx data buffer into the USB peripheral memory. I had expected
> zero copy. During copying, interrupts are disabled.
>
> Basically the USB "framework" would need to be rewritten specifically
> for zero copy operation, if the hardware actually allows that.
unfortunately the old USB peripheral in the sam7s does not have DMA, you
have to use FIFO / MMIO to put the data onto USB. It's really sad,
almost all other peripherals can do DMA, but not the USB device
controller.
I'd love to investigate this further, but I don't have the time right
now, sorry :/
--
- Harald Welte <laforge at gnumonks.org> http://laforge.gnumonks.org/
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