drm/i915/guc: Use wait_for_register_fw() while waiting for MMIO response

Waiting for the response status in scratch register can be done
using our generic function. Let's use it.

v2: rebased

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170407160145.181328-2-michal.wajdeczko@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_uc.c

@@ -359,19 +359,6 @@ void intel_uc_fini_hw(struct drm_i915_private *dev_priv)
 	i915_ggtt_disable_guc(dev_priv);
 }
 
-/*
- * Read GuC command/status register (SOFT_SCRATCH_0)
- * Return true if it contains a response rather than a command
- */
-static bool guc_recv(struct intel_guc *guc, u32 *status)
-{
-	struct drm_i915_private *dev_priv = guc_to_i915(guc);
-
-	u32 val = I915_READ(SOFT_SCRATCH(0));
-	*status = val;
-	return INTEL_GUC_RECV_IS_RESPONSE(val);
-}
-
 /*
  * This function implements the MMIO based host to GuC interface.
  */
@@ -399,13 +386,14 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
 	I915_WRITE(GUC_SEND_INTERRUPT, GUC_SEND_TRIGGER);
 
 	/*
-	 * Fast commands should complete in less than 10us, so sample quickly
-	 * up to that length of time, then switch to a slower sleep-wait loop.
-	 * No inte_guc_send command should ever take longer than 10ms.
+	 * No GuC command should ever take longer than 10ms.
+	 * Fast commands should still complete in 10us.
 	 */
-	ret = wait_for_us(guc_recv(guc, &status), 10);
-	if (ret)
-		ret = wait_for(guc_recv(guc, &status), 10);
+	ret = __intel_wait_for_register_fw(dev_priv,
+					   SOFT_SCRATCH(0),
+					   INTEL_GUC_RECV_MASK,
+					   INTEL_GUC_RECV_MASK,
+					   10, 10, &status);
 	if (status != INTEL_GUC_STATUS_SUCCESS) {
 		/*
 		 * Either the GuC explicitly returned an error (which