On Fri, Mar 26, 2021 at 01:05:26PM +0100, Christoph Hellwig wrote: > On Fri, Mar 26, 2021 at 12:03:03PM +0000, Robin Murphy wrote: > > This might happen to work out, but is far from correct. Just wait until you > > try it on a platform where the USB controller is behind an IOMMU... > > > > It looks like something is more fundamentally wrong here - the device > > passed to DMA API calls must be the actual hardware device performing the > > DMA, which in USB-land I believe means the controller's sysdev. > > The shiny new usb_intf_get_dma_device API provides the device to use. Thanks Robin and Christoph for the feedback. If I understand correctly, usb_intf_get_dma_device API is mainly for usb host drivers? I just found usb_gadget_map_request_by_dev API: does it make sense to replace usb_gadget_map_request with usb_gadget_map_request_by_dev so we can pass the actual DMA-capable hardware device (aspeed-vhub platform device) to the API? Cheers, Tao
