drm/i915: allow force wake at init time on VLV v2

We need to set the 'allow force wake' bit to enable forcewake handling
later on.

v2: split from clock gating patch (Jani)
    check for allowwakeack (Ville)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1417fc6..d554b21 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4010,7 +4010,16 @@
 	int ret;
 
 	mutex_lock(&dev->struct_mutex);
+
+	if (IS_VALLEYVIEW(dev)) {
+		/* VLVA0 (potential hack), BIOS isn't actually waking us */
+		I915_WRITE(VLV_GTLC_WAKE_CTRL, 1);
+		if (wait_for((I915_READ(VLV_GTLC_PW_STATUS) & 1) == 1, 10))
+			DRM_DEBUG_DRIVER("allow wake ack timed out\n");
+	}
+
 	i915_gem_init_global_gtt(dev);
+
 	ret = i915_gem_init_hw(dev);
 	mutex_unlock(&dev->struct_mutex);
 	if (ret) {