On 22.06.22 12:03, David Laight wrote: > Yes, being able to do short transfers from buffer space in the urb > would save all the issues about having to allocate an extra > buffer to avoid DMA from stack. That is just as hard to do for DMA coherency. > Indeed for XHCI there is a bit that allows 8 bytes of data to > replace the pointer in the ring structure itself. > I don't remember the driver every doing that. XHCI does use it. There was even a bug with endianness. Regards Oliver
