On 13/09/2019 16:01, Paolo Bonzini wrote:
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.
Oh, that bit of usbdev_mmap() is already known to be pretty much totally
bogus for various reasons - there have been a few threads about it, of
which I think [1] is both the most recent and the most informative.
There was another patch[2], but that might have stalled (and might need
reworking with additional hcd_uses_dma() checks anyway).
Robin.
[1]
https://lore.kernel.org/linux-arm-kernel/20190808084636.GB15080@priv-mua.localdomain/
[2]
https://lore.kernel.org/linux-usb/20190801220134.3295-1-gavi...@thegavinli.com/
