drm/i915: Just clear the mmiodebug before a register access

When we enable the per-register access mmiodebug, it is to detect which
access is illegal. Reporting on earlier untraced access outside of the
mmiodebug does not help debugging (as the suspicion is immediately put
upon the current register which is not at fault)!

References: https://bugs.freedesktop.org/show_bug.cgi?id=97985
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/20161003124516.12388-1-chris@chris-wilson.co.uk
(cherry picked from commit dda960335e020835f7f1c12760e7f0b525b451e2)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index a9b6c936aadd..ee2306a79747 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -796,10 +796,9 @@ __unclaimed_reg_debug(struct drm_i915_private *dev_priv,
                       const bool read,
                       const bool before)
 {
-        if (WARN(check_for_unclaimed_mmio(dev_priv),
-                 "Unclaimed register detected %s %s register 0x%x\n",
-                 before ? "before" : "after",
-                 read ? "reading" : "writing to",
+        if (WARN(check_for_unclaimed_mmio(dev_priv) && !before,
+                 "Unclaimed %s register 0x%x\n",
+                 read ? "read from" : "write to",
                  i915_mmio_reg_offset(reg)))
                 i915.mmio_debug--; /* Only report the first N failures */
 }