drm/i915: Provide an assert for when we expect forcewake to be held

Add assert_forcewakes_active() (the complementary function to
assert_forcewakes_inactive) that documents the requirement of a
function for its callers to be holding the forcewake ref (i.e. the
function is part of a sequence over which RC6 must be prevented).

One such example is during ringbuffer reset, where RC6 must be held
across the whole reinitialisation sequence.

v2: Include debug information in the WARN so we know which fw domain is
missing.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> #v1
Link: https://patchwork.freedesktop.org/patch/msgid/20171009110301.21705-5-chris@chris-wilson.co.uk

1 files changed, 17 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index b3c3f94fc7e4..983617b5b338 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -626,7 +626,23 @@ void assert_forcewakes_inactive(struct drm_i915_private *dev_priv)
 	if (!dev_priv->uncore.funcs.force_wake_get)
 		return;
 
-	WARN_ON(dev_priv->uncore.fw_domains_active);
+	WARN(dev_priv->uncore.fw_domains_active,
+	     "Expected all fw_domains to be inactive, but %08x are still on\n",
+	     dev_priv->uncore.fw_domains_active);
+}
+
+void assert_forcewakes_active(struct drm_i915_private *dev_priv,
+			      enum forcewake_domains fw_domains)
+{
+	if (!dev_priv->uncore.funcs.force_wake_get)
+		return;
+
+	assert_rpm_wakelock_held(dev_priv);
+
+	fw_domains &= dev_priv->uncore.fw_domains;
+	WARN(fw_domains & ~dev_priv->uncore.fw_domains_active,
+	     "Expected %08x fw_domains to be active, but %08x are off\n",
+	     fw_domains, fw_domains & ~dev_priv->uncore.fw_domains_active);
 }
 
 /* We give fast paths for the really cool registers */