[Intel-gfx] [PATCH] drm/i915: Flush the PTEs after updating them before suspend

[Chris Wilson]

As we use WC updates of the PTE, we are responsible for notifying the
hardware when to flush its TLBs. Do so after we zap all the PTEs before
suspend (and the BIOS tries to read our GTT).

Fixes a regression from

commit 828c79087cec61eaf4c76bb32c222fbe35ac3930
Author: Ben Widawsky <benjamin.widawsky at intel.com>
Date:   Wed Oct 16 09:21:30 2013 -0700

    drm/i915: Disable GGTT PTEs on GEN6+ suspend

that survived and continue to cause harm even after

commit e568af1c626031925465a5caaab7cca1303d55c7
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Wed Mar 26 20:08:20 2014 +0100

    drm/i915: Undo gtt scratch pte unmapping again

v2: Trivial rebase.
v3: Fixes requires pointer dances.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82340
Tested-by: ming.yao at intel.com
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: stable at vger.kernel.org
Cc: Takashi Iwai <tiwai at suse.de>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Cc: Todd Previte <tprevite at gmail.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 1411613f2174..e42925f76b4b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1310,6 +1310,16 @@ void i915_check_and_clear_faults(struct drm_device *dev)
 	POSTING_READ(RING_FAULT_REG(&dev_priv->ring[RCS]));
 }
 
+static void i915_ggtt_flush(struct drm_i915_private *dev_priv)
+{
+	if (INTEL_INFO(dev_priv->dev)->gen < 6) {
+		intel_gtt_chipset_flush();
+	} else {
+		I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
+		POSTING_READ(GFX_FLSH_CNTL_GEN6);
+	}
+}
+
 void i915_gem_suspend_gtt_mappings(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1326,6 +1336,8 @@ void i915_gem_suspend_gtt_mappings(struct drm_device *dev)
 				       dev_priv->gtt.base.start,
 				       dev_priv->gtt.base.total,
 				       true);
+
+	i915_ggtt_flush(dev_priv);
 }
 
 void i915_gem_restore_gtt_mappings(struct drm_device *dev)
@@ -1378,7 +1390,7 @@ void i915_gem_restore_gtt_mappings(struct drm_device *dev)
 		gen6_write_pdes(container_of(vm, struct i915_hw_ppgtt, base));
 	}
 
-	i915_gem_chipset_flush(dev);
+	i915_ggtt_flush(dev_priv);
 }
 
 int i915_gem_gtt_prepare_object(struct drm_i915_gem_object *obj)
-- 
2.1.0