On Mon, 2018-03-19 at 22:50 -0400, Sinan Kaya wrote: > Code includes wmb() followed by writel(). writel() already has a > barrier on some architectures like arm64. > > This ends up CPU observing two barriers back to back before executing > the register write. > > Since code already has an explicit barrier call, changing writel() to > writel_relaxed(). > > Signed-off-by: Sinan Kaya <[email protected]> > --- > drivers/scsi/hpsa.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h > index 018f980..c7d7e6a 100644 > --- a/drivers/scsi/hpsa.h > +++ b/drivers/scsi/hpsa.h > @@ -599,7 +599,7 @@ static unsigned long > SA5_ioaccel_mode1_completed(struct ctlr_info *h, u8 q) > * but with current driver design this is easiest. > */ > wmb(); > - writel((q << 24) | rq->current_entry, h->vaddr + > + writel_relaxed((q << 24) | rq->current_entry, h- > >vaddr + > IOACCEL_MODE1_CONSUMER_INDEX); > atomic_dec(&h->commands_outstanding); > }
This looks like it would work for the x86_64 and arm because of how its defined architecture specific for the x86_64 and the arm64 I guess its up to Don and the driver folks and if its worth the change. I am generally not a fan of messing with these barrier things though. Reviewed-by: Laurence Oberman <[email protected]>
