On Friday 03 April 2009, Haavard Skinnemoen wrote: > David Brownell wrote: > > In that case you'd have to arrange for a short RX packet to > > stop the DMA queue processing. (I've never seen peripheral > > side hardware with DMA that works well enough to support this > > type of implementation strategy.) > > Actually, the Atmel USBA controller (for AVR32 and AT91) has a "stop > DMA on endpoint interrupt" bit which can probably be used to achieve > this. But I don't think the driver is currently queueing DMA requests as > aggressively as it could, so I don't think it will make any difference > unless the queueing code is optimized a bit. The net2280 chips "should" be able to support it too ... but there were so many "gotcha!" cases that queued DMA is not the default. (Likely newer chips in that series got better. That driver had to accomodate bugs in the first developer silicon... now obsolete.) It'd be nice if some controller drivers *did* start supporting that model. Function and gadget drivers might need to adapt a bit to leverage the performance possibilities. - Dave -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
