drm/i915: Markup paired operations on display power domains

The majority of runtime-pm operations are bounded and scoped within a
function; these are easy to verify that the wakeref are handled
correctly. We can employ the compiler to help us, and reduce the number
of wakerefs tracked when debugging, by passing around cookies provided
by the various rpm_get functions to their rpm_put counterpart. This
makes the pairing explicit, and given the required wakeref cookie the
compiler can verify that we pass an initialised value to the rpm_put
(quite handy for double checking error paths).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-16-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_i2c.c

@@ -697,12 +697,13 @@ out:
 static int
 gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
 {
-	struct intel_gmbus *bus = container_of(adapter, struct intel_gmbus,
-					       adapter);
+	struct intel_gmbus *bus =
+		container_of(adapter, struct intel_gmbus, adapter);
 	struct drm_i915_private *dev_priv = bus->dev_priv;
+	intel_wakeref_t wakeref;
 	int ret;
 
-	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
+	wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 
 	if (bus->force_bit) {
 		ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
@@ -714,17 +715,16 @@ gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
 			bus->force_bit |= GMBUS_FORCE_BIT_RETRY;
 	}
 
-	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
+	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS, wakeref);
 
 	return ret;
 }
 
 int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
 {
-	struct intel_gmbus *bus = container_of(adapter, struct intel_gmbus,
-					       adapter);
+	struct intel_gmbus *bus =
+		container_of(adapter, struct intel_gmbus, adapter);
 	struct drm_i915_private *dev_priv = bus->dev_priv;
-	int ret;
 	u8 cmd = DRM_HDCP_DDC_AKSV;
 	u8 buf[DRM_HDCP_KSV_LEN] = { 0 };
 	struct i2c_msg msgs[] = {
@@ -741,8 +741,10 @@ int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
 			.buf = buf,
 		}
 	};
+	intel_wakeref_t wakeref;
+	int ret;
 
-	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
+	wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
 	mutex_lock(&dev_priv->gmbus_mutex);
 
 	/*
@@ -753,7 +755,7 @@ int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
 	ret = do_gmbus_xfer(adapter, msgs, ARRAY_SIZE(msgs), GMBUS_AKSV_SELECT);
 
 	mutex_unlock(&dev_priv->gmbus_mutex);
-	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS);
+	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS, wakeref);
 
 	return ret;
 }