On Wed, 14 Nov 2012 11:06:42 -0800
Ben Widawsky <ben at bwidawsk.net> wrote:
> On Wed, 14 Nov 2012 09:15:14 +0000
> Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> > The bspec was recently updated to remove the ability to update the
> > semaphore using the MI_SEMAPHORE_BOX command, the ability to wait upon
> > the semaphore value remained. Instead the advice is to update the
> > register using the MI_LOAD_REGISTER_IMM command. In cursory testing,
> > semaphores continue to function - the question is whether this fixes
> > some of the deadlocks where the semaphore registers contained stale
> > values?
> >
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Daniel J Blueman <daniel at quora.org>
> Reviewed-by: Ben Widawsky <ben at bwidawsk.net>
Tested-by: Ben Widawsky <ben at bwidawsk.net>
> > ---
> > drivers/gpu/drm/i915/intel_ringbuffer.c | 7 ++-----
> > 1 file changed, 2 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > index ee4abc5..dd2e7db 100644
> > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> > @@ -554,12 +554,9 @@ update_mboxes(struct intel_ring_buffer *ring,
> > u32 seqno,
> > u32 mmio_offset)
> > {
> > - intel_ring_emit(ring, MI_SEMAPHORE_MBOX |
> > - MI_SEMAPHORE_GLOBAL_GTT |
> > - MI_SEMAPHORE_REGISTER |
> > - MI_SEMAPHORE_UPDATE);
> > - intel_ring_emit(ring, seqno);
> > + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
> > intel_ring_emit(ring, mmio_offset);
> > + intel_ring_emit(ring, seqno);
> > }
> >
> > /**
>
>
>
--
Ben Widawsky, Intel Open Source Technology Center
