On Wed, 23 Oct 2019, Christoph Hellwig wrote:
> On Mon, Oct 21, 2019 at 11:48:06AM -0400, Alan Stern wrote:
> > There is no longer any reason to keep the virt_boundary_mask setting
> > for usb-storage. It was needed in the first place only for handling
> > devices with a block size smaller than the maxpacket size and where
> > the host controller was not capable of fully general scatter-gather
> > operation (that is, able to merge two SG segments into a single USB
> > packet). But:
> >
> > High-speed or slower connections never use a bulk maxpacket
> > value larger than 512;
> >
> > The SCSI layer does not handle block devices with a block size
> > smaller than 512 bytes;
> >
> > All the host controllers capable of SuperSpeed operation can
> > handle fully general SG;
> >
> > Since commit ea44d190764b ("usbip: Implement SG support to
> > vhci-hcd and stub driver") was merged, the USB/IP driver can
> > also handle SG.
> >
> > Therefore all supported device/controller combinations should be okay
> > with no need for any special virt_boundary_mask. So in order to fix
> > the swiotlb problem, this patch reverts commit 747668dbc061.
>
> That's great to know. The same should also apply to uas, shouldn't
> it?
Ah, yes, excellent point -- I had forgotten about it. Additional patch
coming up soon...
Alan Stern
> Otherwise:
>
> Acked-by: Christoph Hellwig <hch@xxxxxx>
