From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [PATCH] drm/i915: correctly order the ring init sequence Date: Tue, 07 Aug 2012 15:32:42 +0300 Message-ID: <87y5lqevbp.fsf@intel.com> References: <1344326054-10244-1-git-send-email-daniel.vetter@ffwll.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTP id 777319E77F for ; Tue, 7 Aug 2012 05:29:08 -0700 (PDT) In-Reply-To: <1344326054-10244-1-git-send-email-daniel.vetter@ffwll.ch> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Intel Graphics Development Cc: Daniel Vetter , stable@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org On Tue, 07 Aug 2012, Daniel Vetter 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 > > Cc: stable@vger.kernel.org > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50522 > Tested-by: Yang Guang > Signed-off-by: Daniel Vetter > --- > 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@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx