On 13/09/19 15:02, Greg Kroah-Hartman wrote: > Look at linux-next, we "should" have fixed up hcd_buffer_alloc() now to > not need this type of thing. If we got it wrong, please let us know and > then yes, a fix like this would be most appreciated :) I still see /* some USB hosts just use PIO */ if (!hcd_uses_dma(hcd)) { *dma = ~(dma_addr_t) 0; return kmalloc(size, mem_flags); } in linux-next's hcd_buffer_alloc and also in usb.git's usb-next branch. I also see the same if (remap_pfn_range(vma, vma->vm_start, virt_to_phys(usbm->mem) >> PAGE_SHIFT, size, vma->vm_page_prot) < 0) { ... } in usbdev_mmap. Of course it's possible that I'm looking at the wrong branch, or just being dense. Paolo