On Wed, May 20, 2020 at 06:41:16AM +0000, Tejas Joglekar wrote:
> >> + urb->transfer_buffer = temp;
> >> + urb->transfer_dma = dma_map_single(hcd->self.sysdev,
> >> + urb->transfer_buffer,
> >> + urb->transfer_buffer_length,
> >> + dir);
> >> +
> >> + if (dma_mapping_error(hcd->self.sysdev,
> >> + urb->transfer_dma)) {
> >> + ret = -EAGAIN;
> >> + kfree(temp);
> >> + } else {
> >> + urb->transfer_flags |= URB_DMA_MAP_SINGLE;
> >
> > Not sure if using URB_DMA_MAP_SINGLE to flag that this urb is boucebuffered is
> > appropriate.
> >
> > If Greg or Alan don't object then it's fine for me as well.
> >
> >
> >
> @Greg/Alan do you suggest any change for the flag here?
This requires care, because the core will already have set other flags
for this URB. I don't remember the details and I don't have time to
check them now. But it wouldn't be at all surprising if the core
doesn't expect an URB both to use SG and to use DMA_MAP_SINGLE.
Alan Stern
