On Wed, Jan 23, 2013 at 7:15 AM, CAI Qian <caiq...@redhat.com> wrote: > Hello Daniel, > > Could you please help ACK/NAK this back-port patch for the stable-3.7.y? > It fixed up the context and dropped the modification for > vlv_force_wake_reset() due to it was only introduced later.
Yeah, looks good. -Daniel > > Regards, > CAI Qian > > From b514407547890686572606c9dfa4b7f832db9958 Mon Sep 17 00:00:00 2001 > From: Jani Nikula <jani.nik...@intel.com> > Date: Thu, 17 Jan 2013 10:24:09 +0200 > Subject: [PATCH] drm/i915: fix FORCEWAKE posting reads > > We stopped reading FORCEWAKE for posting reads in > > commit 8dee3eea3ccd3b6c00a8d3a08dd715d6adf737dd > Author: Ben Widawsky <b...@bwidawsk.net> > Date: Sat Sep 1 22:59:50 2012 -0700 > > drm/i915: Never read FORCEWAKE > > and started using something from the same cacheline instead. On the > bug reporter's machine this broke entering rc6 states after a > suspend/resume cycle. It turns out reading ECOBUS as posting read > worked fine, while GTFIFODBG did not, preventing RC6 states after > suspend/resume per the bug report referenced below. It's not entirely > clear why, but clearly GTFIFODBG was nowhere near the same cacheline > or address range as FORCEWAKE. > > Trying out various registers for posting reads showed that all tested > registers for which NEEDS_FORCE_WAKE() (in i915_drv.c) returns true > work. Conversely, most (but not quite all) registers for which > NEEDS_FORCE_WAKE() returns false do not work. Details in the referenced > bug. > > Based on the above, add posting reads on ECOBUS where GTFIFODBG was > previously relied on. > > In true cargo cult spirit, add posting reads for FORCEWAKE_VLV writes as > well, but instead of ECOBUS, use FORCEWAKE_ACK_VLV which is in the same > address range as FORCEWAKE_VLV. > > v2: Add more details to the commit message. No functional changes. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=52411 > Reported-and-tested-by: Alexander Bersenev <b...@hackerdom.ru> > CC: Ben Widawsky <b...@bwidawsk.net> > Signed-off-by: Jani Nikula <jani.nik...@intel.com> > Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk> > Cc: stable@vger.kernel.org > [danvet: add cc: stable and make the commit message a bit clearer that > this is a regression fix and what exactly broke.] > Signed-off-by: Daniel Vetter <daniel.vet...@ffwll.ch> > Signed-off-by: CAI Qian <caiq...@redhat.com> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > index eaaff3c..a01ab2a 100644 > --- a/drivers/gpu/drm/i915/intel_pm.c > +++ b/drivers/gpu/drm/i915/intel_pm.c > @@ -4014,7 +4014,8 @@ static void __gen6_gt_force_wake_get(struct > drm_i915_private *dev_priv) > DRM_ERROR("Timed out waiting for forcewake old ack to > clear.\n"); > > I915_WRITE_NOTRACE(FORCEWAKE, 1); > - POSTING_READ(ECOBUS); /* something from same cacheline, but > !FORCEWAKE */ > + /* something from same cacheline, but !FORCEWAKE */ > + POSTING_READ(ECOBUS); > > if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) & 1), > FORCEWAKE_ACK_TIMEOUT_MS)) > @@ -4037,7 +4038,8 @@ static void __gen6_gt_force_wake_mt_get(struct > drm_i915_private *dev_priv) > DRM_ERROR("Timed out waiting for forcewake old ack to > clear.\n"); > > I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_ENABLE(1)); > - POSTING_READ(ECOBUS); /* something from same cacheline, but > !FORCEWAKE */ > + /* something from same cacheline, but !FORCEWAKE */ > + POSTING_READ(ECOBUS); > > if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) & 1), > FORCEWAKE_ACK_TIMEOUT_MS)) > @@ -4074,14 +4076,16 @@ void gen6_gt_check_fifodbg(struct drm_i915_private > *dev_priv) > static void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv) > { > I915_WRITE_NOTRACE(FORCEWAKE, 0); > - /* gen6_gt_check_fifodbg doubles as the POSTING_READ */ > + /* something from same cacheline, but !FORCEWAKE */ > + POSTING_READ(ECOBUS); > gen6_gt_check_fifodbg(dev_priv); > } > > static void __gen6_gt_force_wake_mt_put(struct drm_i915_private *dev_priv) > { > I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_DISABLE(1)); > - /* gen6_gt_check_fifodbg doubles as the POSTING_READ */ > + /* something from same cacheline, but !FORCEWAKE_MT */ > + POSTING_READ(ECOBUS); > gen6_gt_check_fifodbg(dev_priv); > } > > @@ -4136,7 +4140,8 @@ static void vlv_force_wake_get(struct drm_i915_private > *dev_priv) > static void vlv_force_wake_put(struct drm_i915_private *dev_priv) > { > I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_DISABLE(1)); > - /* The below doubles as a POSTING_READ */ > + /* something from same cacheline, but !FORCEWAKE_VLV */ > + POSTING_READ(FORCEWAKE_ACK_VLV); > gen6_gt_check_fifodbg(dev_priv); > } -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
