drm/i915: Setup static bias for GPU

Based on the spec, Setting up static BIAS for GPU to improve the
rps performace.

v2: rename reg defn to match spec. (Ville)

v3: Updated bias setting for chv (Deepak)
Signed-off-by: Deepak S <deepak.s@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -670,6 +670,12 @@ enum skl_disp_power_wells {
 #define   FB_FMAX_VMIN_FREQ_LO_SHIFT		27
 #define   FB_FMAX_VMIN_FREQ_LO_MASK		0xf8000000
 
+#define VLV_TURBO_SOC_OVERRIDE	0x04
+#define 	VLV_OVERRIDE_EN	1
+#define 	VLV_SOC_TDP_EN	(1 << 1)
+#define 	VLV_BIAS_CPU_125_SOC_875 (6 << 2)
+#define 	CHV_BIAS_CPU_50_SOC_50 (3 << 2)
+
 #define VLV_CZ_CLOCK_TO_MILLI_SEC		100000
 
 /* vlv2 north clock has */

drivers/gpu/drm/i915/intel_pm.c

@@ -5082,6 +5082,12 @@ static void cherryview_enable_rps(struct drm_device *dev)
 		   GEN6_RP_UP_BUSY_AVG |
 		   GEN6_RP_DOWN_IDLE_AVG);
 
+	/* Setting Fixed Bias */
+	val = VLV_OVERRIDE_EN |
+		  VLV_SOC_TDP_EN |
+		  CHV_BIAS_CPU_50_SOC_50;
+	vlv_punit_write(dev_priv, VLV_TURBO_SOC_OVERRIDE, val);
+
 	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
 
 	/* RPS code assumes GPLL is used */
@@ -5166,6 +5172,12 @@ static void valleyview_enable_rps(struct drm_device *dev)
 
 	I915_WRITE(GEN6_RC_CONTROL, rc6_mode);
 
+	/* Setting Fixed Bias */
+	val = VLV_OVERRIDE_EN |
+		  VLV_SOC_TDP_EN |
+		  VLV_BIAS_CPU_125_SOC_875;
+	vlv_punit_write(dev_priv, VLV_TURBO_SOC_OVERRIDE, val);
+
 	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
 
 	/* RPS code assumes GPLL is used */