Re: [PATCH] usb: xhci: Add 2nd memory barrier to giveback_first_trb()

2013-12-13 Thread Sarah Sharp
On Wed, Nov 13, 2013 at 10:24:00AM -, David Laight wrote: > > Greg KH wrote: > > On Tue, Nov 12, 2013 at 01:58:05PM -, David Laight wrote: > > > > > > There needs to be a wmb() barrier between the write to the cycle bit > > > in the first TRB and the write to the doorbell register. > > > >

RE: [PATCH] usb: xhci: Add 2nd memory barrier to giveback_first_trb()

2013-11-13 Thread David Laight
> Greg KH wrote: > On Tue, Nov 12, 2013 at 01:58:05PM -, David Laight wrote: > > > > There needs to be a wmb() barrier between the write to the cycle bit > > in the first TRB and the write to the doorbell register. > > > > Since it isn't needed in the other places the doobell is rung > > (becau

Re: [PATCH] usb: xhci: Add 2nd memory barrier to giveback_first_trb()

2013-11-12 Thread Greg KH
On Tue, Nov 12, 2013 at 01:58:05PM -, David Laight wrote: > > There needs to be a wmb() barrier between the write to the cycle bit > in the first TRB and the write to the doorbell register. > > Since it isn't needed in the other places the doobell is rung > (because the ring contents haven't

[PATCH] usb: xhci: Add 2nd memory barrier to giveback_first_trb()

2013-11-12 Thread David Laight
There needs to be a wmb() barrier between the write to the cycle bit in the first TRB and the write to the doorbell register. Since it isn't needed in the other places the doobell is rung (because the ring contents haven't been changed) add it to giveback_first_trb() rather than somewhere later.