drm/i915: Store the requested frequency whilst RPS is disabled

If intel_set_rps() is called whilst the hw is disabled, just store the
requested frequency (from the user) for application when we wake the hw
up.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170220094713.22874-2-chris@chris-wilson.co.uk
Reviewed-by: Radoslaw Szwichtenberg <radoslaw.szwichtenberg@intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -5105,6 +5105,11 @@ int intel_set_rps(struct drm_i915_private *dev_priv, u8 val)
 	GEM_BUG_ON(val > dev_priv->rps.max_freq);
 	GEM_BUG_ON(val < dev_priv->rps.min_freq);
 
+	if (!dev_priv->rps.enabled) {
+		dev_priv->rps.cur_freq = val;
+		return 0;
+	}
+
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		err = valleyview_set_rps(dev_priv, val);
 	else