From 8dee3eea3ccd3b6c00a8d3a08dd715d6adf737dd Mon Sep 17 00:00:00 2001 From: Ben Widawsky Date: Sat, 1 Sep 2012 22:59:50 -0700 Subject: [PATCH] drm/i915: Never read FORCEWAKE The same designer from the previous patch has told us to never read FORCEWAKE. We only do this for the POSTING_READ(), so simply change that to something within the same cacheline (for no reason in particular other than it sounds nice). In the _mt case we can leverage the gtfifodbg check for the POSTING_READ. This partially reverts commit 6af2d180f82151cf3d58952e35a4f96e45bc453a Author: Daniel Vetter Date: Thu Jul 26 16:24:50 2012 +0200 drm/i915: fix forcewake related hangs on snb v2: commit message, comments about posting read from (Daniel) Note: vlv forcewake doesn't need any changes for this special treatment since FORCEWAKE_VLV is in a totally different register range, and the readback FORCEWAKE_ACK_VLV readback that follows is in the same range. Signed-off-by: Ben Widawsky Acked-by: Chris Wilson [danvet: Added note.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_pm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 31e47387ab9..36c64091bc9 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -3969,7 +3969,7 @@ 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(FORCEWAKE); + POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE */ if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) & 1), FORCEWAKE_ACK_TIMEOUT_MS)) @@ -3992,7 +3992,7 @@ 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(FORCEWAKE_MT); + POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE */ if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) & 1), FORCEWAKE_ACK_TIMEOUT_MS)) @@ -4029,14 +4029,14 @@ 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); - POSTING_READ(FORCEWAKE); + /* gen6_gt_check_fifodbg doubles as the POSTING_READ */ 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)); - POSTING_READ(FORCEWAKE_MT); + /* gen6_gt_check_fifodbg doubles as the POSTING_READ */ gen6_gt_check_fifodbg(dev_priv); }