drm/i915: Only warn the first time we attempt to mmio whilst suspended

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>

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index c8796316d242fd921ecd68e360d18a9f819bbcab..b6c063cad59b1916ba07e660588b0892f5e0fe55 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -451,8 +451,8 @@ hsw_unclaimed_reg_check(struct drm_i915_private *dev_priv, u32 reg)
 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");
 }
 
 #define REG_READ_HEADER(x) \