On Thu, Aug 22, 2019 at 09:40:11AM -0700, Greg KH wrote: > On Fri, Aug 09, 2019 at 12:54:34AM +0900, Suwan Kim wrote: > > vhci doesn’t do DMA for remote device. Actually, the real DMA > > operation is done by network card driver. vhci just passes virtual > > address of the buffer to the network stack, so vhci doesn’t use and > > need dma address of the buffer of the URB. > > > > But HCD provides DMA mapping and unmapping function by default. > > Moreover, it causes unnecessary DMA mapping and unmapping which > > will be done again at the NIC driver and it wastes CPU cycles. > > So, implement map_urb_for_dma and unmap_urb_for_dma function for > > vhci in order to skip the DMA mapping and unmapping procedure. > > > > When it comes to supporting SG for vhci, it is useful to use native > > SG list (urb->num_sgs) instead of mapped SG list because DMA mapping > > fnuction can adjust the number of SG list (urb->num_mapped_sgs). > > And vhci_map_urb_for_dma() prevents isoc pipe from using SG as > > hcd_map_urb_for_dma() does. > > > > Signed-off-by: Suwan Kim <suwan.kim027@xxxxxxxxx> > > Can you please redo this patch based on my usb-next branch that has > Christoph's DMA changes in it? It should make your change much simpler > and smaller. > > Please do that and resend the whole series. I just sent v6 patch. And I discarded patch1 and patch1 is no longer needed because vhci doesn't set set HCD_DMA flag that is introduced by Christoph's patch. So I sent only patch 2 as v6. Regards Suwan Kim
