| Message ID | 1398808360-3674-10-git-send-email-benjamin.widawsky@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 29, 2014 at 02:52:36PM -0700, Ben Widawsky wrote: > As Ville points out, it's possible/probable we don't actually need this. > Potentially, this validates the letter of the spec, and not the spirit. > > Ville: > > I discussed this on irc w/ Ben, and I was suggesting we don't need to > > poll. Polling apparently can be used as a workaround for certain > > hardware issues, but it looks like those issues shouldn't affect us, > > for the momemnt at least. So my suggestion was to try w/o polling > > first (since there could be some power cost to polling) and add the > > poll bit if problems arise. I had another look at bspec and there seems to be a bit more text about the signal mode stuff since the last time I looked. But it still looks like signal mode should be OK for production hardware. One of the workarounds says that !RCS rings can lose the PPGTT page directory information when becoming idle while waiting for a semaphore. The workaround is either reprogamming the PPGTT after semaphore wait or disabling the idle message. We already disable the idle message for RCS for some other reason but not for the other rings. Doing that for all rings seems like the easier option here. This seems to apply to production hardware. There's another idle message disable w/a (using another bit which maybe disables more rc states?) but that seems to affect only pre-production hardware. Here the other option here is to use polling instead. > > Signed-off-by: Ben Widawsky <ben@bwidawsk.net> > --- > drivers/gpu/drm/i915/intel_ringbuffer.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c > index 31b1f3c..e7748ef 100644 > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > @@ -842,6 +842,7 @@ gen8_ring_sync(struct intel_ring_buffer *waiter, > > intel_ring_emit(waiter, MI_SEMAPHORE_WAIT | > MI_SEMAPHORE_GLOBAL_GTT | > + MI_SEMAPHORE_POLL | > MI_SEMAPHORE_SAD_GTE_SDD); > intel_ring_emit(waiter, seqno); > intel_ring_emit(waiter, > -- > 1.9.2 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 31b1f3c..e7748ef 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -842,6 +842,7 @@ gen8_ring_sync(struct intel_ring_buffer *waiter, intel_ring_emit(waiter, MI_SEMAPHORE_WAIT | MI_SEMAPHORE_GLOBAL_GTT | + MI_SEMAPHORE_POLL | MI_SEMAPHORE_SAD_GTE_SDD); intel_ring_emit(waiter, seqno); intel_ring_emit(waiter,