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From: Ben Widawsky <ben@bwidawsk.net>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH v2 3/5] drm/i915: fix rc6 initialization on Ironlake
Date: Sat, 19 Mar 2011 18:14:28 -0700
Message-ID: <1300583670-3489-3-git-send-email-ben@bwidawsk.net> (raw)
In-Reply-To: <b9dded$iah4v5@orsmga002.jf.intel.com>

There is a race condition between setting PWRCTXA and executing
MI_SET_CONTEXT. PWRCTXA must not be set until a valid context has been
written (or else the GPU could possible go into rc6, and return to an
invalid context).

Reported-and-Tested-by: Gu Rui <chaos.proton@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=28582
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/i915/intel_display.c |   16 +++++++++++++---
 1 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2e3c626..6c92980 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6602,9 +6602,6 @@ void ironlake_enable_rc6(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	/* rc6 disabled by default due to repeated reports of hanging during
-	 * boot and resume.
-	 */
 	if (!i915_enable_rc6)
 		return;
 
@@ -6638,6 +6635,19 @@ void ironlake_enable_rc6(struct drm_device *dev)
 	OUT_RING(MI_FLUSH);
 	ADVANCE_LP_RING();
 
+	/*
+	 * Wait for the command parser to advance past MI_SET_CONTEXT. The HW
+	 * does an implicit flush, combined with MI_FLUSH above, it should be
+	 * safe to assume that renderctx is valid
+	 */
+	ret = intel_wait_ring_idle(LP_RING(dev_priv));
+	if (ret) {
+		DRM_ERROR("failed to enable ironlake power power savings\n");
+		ironlake_teardown_rc6(dev);
+		mutex_unlock(&dev->struct_mutex);
+		return;
+	}
+
 	I915_WRITE(PWRCTXA, dev_priv->pwrctx->gtt_offset | PWRCTX_EN);
 	I915_WRITE(RSTDBYCTL, I915_READ(RSTDBYCTL) & ~RCX_SW_EXIT);
 	mutex_unlock(&dev->struct_mutex);
-- 
1.7.3.4

  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-18 23:12 [PATCH 0/4] Re-enable RC6 " Ben Widawsky
2011-03-18 23:12 ` [PATCH 1/4] drm/i915: fix ilk rc6 teardown locking Ben Widawsky
2011-03-19  7:44   ` Chris Wilson
2011-03-19 18:38     ` [PATCH v2 " Ben Widawsky
2011-03-19 18:46     ` [PATCH " Keith Packard
2011-03-20  1:14     ` [PATCH v2 1/5] " Ben Widawsky
2011-03-20  1:14     ` [PATCH v2 2/5] drm/1915: ringbuffer wait for idle function Ben Widawsky
2011-03-20  1:14     ` Ben Widawsky [this message]
2011-03-20  1:14     ` [PATCH v2 4/5] drm/i915: debugfs for context information Ben Widawsky
2011-03-20  1:14     ` [PATCH v2 5/5] drm/i915: re-enable rc6 for ironlake Ben Widawsky
2011-03-18 23:12 ` [PATCH 2/4] drm/i915: fix rc6 initialization on Ironlake Ben Widawsky
2011-03-19  7:55   ` Chris Wilson
2011-03-20  0:07     ` Ben Widawsky
2011-03-18 23:12 ` [PATCH 3/4] drm/i915: debugfs for context information Ben Widawsky
2011-03-18 23:12 ` [PATCH 4/4] drm/i915: re-enable rc6 for ironlake Ben Widawsky
2011-04-27  7:49   ` Chris Wilson
2011-04-27 21:20     ` Jesse Barnes
2011-04-27 22:03       ` Chris Wilson
2011-04-27 22:49         ` Jesse Barnes
2011-04-28 17:10           ` Ben Widawsky

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