On Mon, Mar 29, 2021 at 08:17:35AM +0200, Christoph Hellwig wrote: > On Sat, Mar 27, 2021 at 03:17:59PM -0700, Tao Ren wrote: > > 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? > > Oh, right you're dealing with a gadget side driver. Not sure about > the API there, I'll let the relevant maintainers chime in. Given this is not the right path, I will drop the patch and work out a new fix soon (by calling usb_gadget_map_request_by_dev, and with modified subject). Cheers, Tao
