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

commit f856f847b22c52be82f712ea6ada946c6db884d7 upstream.

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>
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>
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 ff80a81b1a84f929cf9a7aacda59608a23e0dc8a..ec28b15f27249510fd1442dcd91dc0c2f9bb0323 100644 (file)
--- 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 */
 }