On Fri, Aug 02, 2019 at 04:22:27PM -0600, shuah wrote: > On 8/2/19 11:36 AM, 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.kim...@gmail.com> > > --- > > drivers/usb/usbip/vhci_hcd.c | 19 +++++++++++++++++++ > > 1 file changed, 19 insertions(+) > > > > diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c > > index 000ab7225717..c62f7fa8118c 100644 > > --- a/drivers/usb/usbip/vhci_hcd.c > > +++ b/drivers/usb/usbip/vhci_hcd.c > > @@ -1288,6 +1288,22 @@ static int vhci_free_streams(struct usb_hcd *hcd, > > struct usb_device *udev, > > return 0; > > } > > +static int vhci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, > > + gfp_t mem_flags) > > +{ > > + if (usb_endpoint_xfer_isoc(&urb->ep->desc) && urb->num_sgs) { > > + WARN_ON(1); > > Don't add WARN_ON. I cleaned them all up recently and don't want new > ones added.
Ok. I will remove it and resend v4. Regards Suwan Kim