drm/i915: add media well to VLV force wake routines v2

We could split this out into a separate routine at some point as an
optimization.

v2: use FORCEWAKE_KERNEL (Ville)

Note: Ville mentioned in his review that he declines to be responsible
if this blows up due to the lack of "readback a register != FW_ACK,
but from the same cacheline" magic we have in other forcewake
implementations.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Bikeshed overtly long lines according to checkpatch.pl. Nope,
this time around I didn't screw up printk message since I've left
those alone.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -4148,6 +4148,8 @@
 #define  FORCEWAKE				0xA18C
 #define  FORCEWAKE_VLV				0x1300b0
 #define  FORCEWAKE_ACK_VLV			0x1300b4
+#define  FORCEWAKE_MEDIA_VLV			0x1300b8
+#define  FORCEWAKE_ACK_MEDIA_VLV		0x1300bc
 #define  FORCEWAKE_ACK_HSW			0x130044
 #define  FORCEWAKE_ACK				0x130090
 #define  VLV_GTLC_WAKE_CTRL			0x130090

drivers/gpu/drm/i915/intel_pm.c

@@ -4404,10 +4404,17 @@ static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
 		DRM_ERROR("Timed out waiting for forcewake old ack to clear.\n");
 
 	I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
+	I915_WRITE_NOTRACE(FORCEWAKE_MEDIA_VLV,
+			   _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
 
 	if (wait_for_atomic((I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & FORCEWAKE_KERNEL),
 			    FORCEWAKE_ACK_TIMEOUT_MS))
-		DRM_ERROR("Timed out waiting for forcewake to ack request.\n");
+		DRM_ERROR("Timed out waiting for GT to ack forcewake request.\n");
+
+	if (wait_for_atomic((I915_READ_NOTRACE(FORCEWAKE_ACK_MEDIA_VLV) &
+			     FORCEWAKE_KERNEL),
+			    FORCEWAKE_ACK_TIMEOUT_MS))
+		DRM_ERROR("Timed out waiting for media to ack forcewake request.\n");
 
 	__gen6_gt_wait_for_thread_c0(dev_priv);
 }
@@ -4415,8 +4422,9 @@ static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
 static void vlv_force_wake_put(struct drm_i915_private *dev_priv)
 {
 	I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_DISABLE(FORCEWAKE_KERNEL));
-	/* something from same cacheline, but !FORCEWAKE_VLV */
-	POSTING_READ(FORCEWAKE_ACK_VLV);
+	I915_WRITE_NOTRACE(FORCEWAKE_MEDIA_VLV,
+			   _MASKED_BIT_DISABLE(FORCEWAKE_KERNEL));
+	/* The below doubles as a POSTING_READ */
 	gen6_gt_check_fifodbg(dev_priv);
 }