[PATCH 3.18 042/183] drm/i915: Only warn the first time we attempt to mmio whilst suspended

Greg Kroah-Hartman
2015-01-25T18:57:41Z

From: Chris Wilson <chris@chris-wilson.co.uk>

commit 2b387059817fd100cddc5a97118d63e3f3fade74 upstream.

In all likelihood we will do a few hundred errnoneous register
operations if we do a single invalid register access whilst the device
is suspended. As each instance causes a WARN, this floods the system
logs and can make the system unresponsive.

The warning was first introduced in
commit b2ec142cb0101f298f8e091c7d75b1ec5b809b65
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Fri Feb 21 13:52:25 2014 -0300

drm/i915: call assert_device_not_suspended at gen6_force_wake_work

and despite the claims the WARN is still encountered in the wild today.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/i915/intel_uncore.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -43,8 +43,8 @@
static void
assert_device_not_suspended(struct drm_i915_private *dev_priv)
{
- WARN(HAS_RUNTIME_PM(dev_priv->dev) && dev_priv->pm.suspended,
- "Device suspended\n");
+ WARN_ONCE(HAS_RUNTIME_PM(dev_priv->dev) && dev_priv->pm.suspended,
+ "Device suspended\n");
}

static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv)