drm/i915: Enable the maxfifo PM5 mode when appropriate on CHV

CHV has a new knob in Punit to select between some memory power savings
modes PM2 and PM5. We can allow the deeper PM5 when maxfifo mode is
enabled, so let's do so in the hopes for moar power savings.

v2: Put the thing into a separate function to avoid churn later
v3: Don't break VLV

Reviewed-by: Vijay Purushothaman <vijay.a.purushothaman@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -566,6 +566,9 @@
 #define   DSPFREQSTAT_MASK			(0x3 << DSPFREQSTAT_SHIFT)
 #define   DSPFREQGUAR_SHIFT			14
 #define   DSPFREQGUAR_MASK			(0x3 << DSPFREQGUAR_SHIFT)
+#define   DSP_MAXFIFO_PM5_STATUS		(1 << 22) /* chv */
+#define   DSP_AUTO_CDCLK_GATE_DISABLE		(1 << 7) /* chv */
+#define   DSP_MAXFIFO_PM5_ENABLE		(1 << 6) /* chv */
 #define   _DP_SSC(val, pipe)			((val) << (2 * (pipe)))
 #define   DP_SSC_MASK(pipe)			_DP_SSC(0x3, (pipe))
 #define   DP_SSC_PWR_ON(pipe)			_DP_SSC(0x0, (pipe))

drivers/gpu/drm/i915/intel_pm.c

@@ -263,13 +263,31 @@ static const struct cxsr_latency *intel_get_cxsr_latency(int is_desktop,
 	return NULL;
 }
 
+static void chv_set_memory_pm5(struct drm_i915_private *dev_priv, bool enable)
+{
+	u32 val;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+
+	val = vlv_punit_read(dev_priv, PUNIT_REG_DSPFREQ);
+	if (enable)
+		val |= DSP_MAXFIFO_PM5_ENABLE;
+	else
+		val &= ~DSP_MAXFIFO_PM5_ENABLE;
+	vlv_punit_write(dev_priv, PUNIT_REG_DSPFREQ, val);
+
+	mutex_unlock(&dev_priv->rps.hw_lock);
+}
+
 void intel_set_memory_cxsr(struct drm_i915_private *dev_priv, bool enable)
 {
 	struct drm_device *dev = dev_priv->dev;
 	u32 val;
 
 	if (IS_VALLEYVIEW(dev)) {
 		I915_WRITE(FW_BLC_SELF_VLV, enable ? FW_CSPWRDWNEN : 0);
+		if (IS_CHERRYVIEW(dev))
+			chv_set_memory_pm5(dev_priv, enable);
 	} else if (IS_G4X(dev) || IS_CRESTLINE(dev)) {
 		I915_WRITE(FW_BLC_SELF, enable ? FW_BLC_SELF_EN : 0);
 	} else if (IS_PINEVIEW(dev)) {