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, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
index 66eae2ce2f29..582771251b57 100644
--- a/drivers/gpu/drm/i915/intel_uncore.h
+++ b/drivers/gpu/drm/i915/intel_uncore.h
@@ -137,6 +137,8 @@ void intel_uncore_resume_early(struct drm_i915_private *dev_priv);
 
 u64 intel_uncore_edram_size(struct drm_i915_private *dev_priv);
 void assert_forcewakes_inactive(struct drm_i915_private *dev_priv);
+void assert_forcewakes_active(struct drm_i915_private *dev_priv,
+			      enum forcewake_domains fw_domains);
 const char *intel_uncore_forcewake_domain_to_str(const enum forcewake_domain_id id);
 
 enum forcewake_domains