On Tue, 07 Aug 2012, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > We may only start to set up the new register values after having > confirmed that the ring is truely off. Otherwise the hw might lose the > newly written register values. This is caught later on in the init > sequence, when we check whether the register writes have stuck. With or without (up to you) the comment clarification discussed in IRC, Reviewed-by: Jani Nikula <jani.nikula at intel.com> > > Cc: stable at vger.kernel.org > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50522 > Tested-by: Yang Guang <guang.a.yang at intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> > --- > drivers/gpu/drm/i915/intel_ringbuffer.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c > index bf0195a..5b19917 100644 > --- a/drivers/gpu/drm/i915/intel_ringbuffer.c > +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c > @@ -289,8 +289,6 @@ static int init_ring_common(struct intel_ring_buffer *ring) > I915_WRITE_HEAD(ring, 0); > ring->write_tail(ring, 0); > > - /* Initialize the ring. */ > - I915_WRITE_START(ring, obj->gtt_offset); > head = I915_READ_HEAD(ring) & HEAD_ADDR; > > /* G45 ring initialization fails to reset head to zero */ > @@ -316,6 +314,10 @@ static int init_ring_common(struct intel_ring_buffer *ring) > } > } > > + /* Initialize the ring. This must happen _after_ we have confirmed that > + * the ring is off (with the above head == 0 check), otherwise the hw > + * might lose the new ring register values. */ > + I915_WRITE_START(ring, obj->gtt_offset); > I915_WRITE_CTL(ring, > ((ring->size - PAGE_SIZE) & RING_NR_PAGES) > | RING_VALID); > -- > 1.7.10.4 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx at lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
