drm/i915: Enable RC6 autodownclocking on Sandybridge

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_reg.h

@@ -283,6 +283,7 @@
 #define RING_CTL(base)		((base)+0x3c)
 #define RING_SYNC_0(base)	((base)+0x40)
 #define RING_SYNC_1(base)	((base)+0x44)
+#define RING_MAX_IDLE(base)	((base)+0x54)
 #define RING_HWS_PGA(base)	((base)+0x80)
 #define RING_HWS_PGA_GEN6(base)	((base)+0x2080)
 #define RING_ACTHD(base)	((base)+0x74)
@@ -3116,4 +3117,62 @@
 
 #define  FORCEWAKE				0xA18C
 #define  FORCEWAKE_ACK				0x130090
+
+#define GEN6_RC_NORMAL_FREQ			0xA008
+#define   GEN6_TURBO_DISABLE			(1<<31)
+#define   GEN6_FREQUENCY(x)			((x)<<25)
+#define   GEN6_OFFSET(x)			((x)<<19)
+#define   GEN6_AGGRESSIVE_TURBO			(0<<15)
+#define GEN6_RC_VIDEO_FREQ			0xA00C
+#define GEN6_RC_CONTROL				0xA090
+#define   GEN6_RC_CTL_RC6pp_ENABLE		(1<<16)
+#define   GEN6_RC_CTL_RC6p_ENABLE		(1<<17)
+#define   GEN6_RC_CTL_RC6_ENABLE		(1<<18)
+#define   GEN6_RC_CTL_RC1e_ENABLE		(1<<20)
+#define   GEN6_RC_CTL_RC7_ENABLE		(1<<22)
+#define   GEN6_RC_CTL_EI_MODE(x)		((x)<<27)
+#define   GEN6_RC_CTL_HW_ENABLE			(1<<31)
+#define GEN6_RP_DOWN_TIMEOUT			0xA010
+#define GEN6_RP_INTERRUPT_LIMITS		0xA014
+#define GEN6_RP_CONTROL				0xA024
+#define   GEN6_RP_MEDIA_TURBO			(1<<11)
+#define   GEN6_RP_USE_NORMAL_FREQ		(1<<9)
+#define   GEN6_RP_MEDIA_IS_GFX			(1<<8)
+#define   GEN6_RP_ENABLE			(1<<7)
+#define   GEN6_RP_UP_BUSY_MAX			(0x2<<3)
+#define   GEN6_RP_DOWN_BUSY_MIN			(0x2<<0)
+#define GEN6_RP_UP_THRESHOLD			0xA02C
+#define GEN6_RP_DOWN_THRESHOLD			0xA030
+#define GEN6_RP_UP_EI				0xA068
+#define GEN6_RP_DOWN_EI				0xA06C
+#define GEN6_RP_IDLE_HYSTERSIS			0xA070
+#define GEN6_RC_STATE				0xA094
+#define GEN6_RC1_WAKE_RATE_LIMIT		0xA098
+#define GEN6_RC6_WAKE_RATE_LIMIT		0xA09C
+#define GEN6_RC6pp_WAKE_RATE_LIMIT		0xA0A0
+#define GEN6_RC_EVALUATION_INTERVAL		0xA0A8
+#define GEN6_RC_IDLE_HYSTERSIS			0xA0AC
+#define GEN6_RC_SLEEP				0xA0B0
+#define GEN6_RC1e_THRESHOLD			0xA0B4
+#define GEN6_RC6_THRESHOLD			0xA0B8
+#define GEN6_RC6p_THRESHOLD			0xA0BC
+#define GEN6_RC6pp_THRESHOLD			0xA0C0
+
+#define GEN6_PMISR				0x44020
+#define GEN6_PMIMR				0x44024
+#define GEN6_PMIIR				0x44028
+#define GEN6_PMIER				0x4402C
+#define  GEN6_PM_MBOX_EVENT			(1<<25)
+#define  GEN6_PM_THERMAL_EVENT			(1<<24)
+#define  GEN6_PM_RP_DOWN_TIMEOUT		(1<<6)
+#define  GEN6_PM_RP_UP_THRESHOLD		(1<<5)
+#define  GEN6_PM_RP_DOWN_THRESHOLD		(1<<4)
+#define  GEN6_PM_RP_UP_EI_EXPIRED		(1<<2)
+#define  GEN6_PM_RP_DOWN_EI_EXPIRED		(1<<1)
+
+#define GEN6_PCODE_MAILBOX			0x138124
+#define   GEN6_PCODE_READY			(1<<31)
+#define   GEN6_PCODE_WRITE_MIN_FREQ_TABLE	0x9
+#define GEN6_PCODE_DATA				0x138128
+
 #endif /* _I915_REG_H_ */

drivers/gpu/drm/i915/intel_display.c

@@ -5842,6 +5842,91 @@ void intel_init_emon(struct drm_device *dev)
 	dev_priv->corr = (lcfuse & LCFUSE_HIV_MASK);
 }
 
+static void gen6_enable_rc6(struct drm_i915_private *dev_priv)
+{
+	int i;
+
+	/* Here begins a magic sequence of register writes to enable
+	 * auto-downclocking.
+	 *
+	 * Perhaps there might be some value in exposing these to
+	 * userspace...
+	 */
+	I915_WRITE(GEN6_RC_STATE, 0);
+	__gen6_force_wake_get(dev_priv);
+
+	/* disable the counters and set determistic thresholds */
+	I915_WRITE(GEN6_RC_CONTROL, 0);
+
+	I915_WRITE(GEN6_RC1_WAKE_RATE_LIMIT, 1000 << 16);
+	I915_WRITE(GEN6_RC6_WAKE_RATE_LIMIT, 40 << 16 | 30);
+	I915_WRITE(GEN6_RC6pp_WAKE_RATE_LIMIT, 30);
+	I915_WRITE(GEN6_RC_EVALUATION_INTERVAL, 125000);
+	I915_WRITE(GEN6_RC_IDLE_HYSTERSIS, 25);
+
+	for (i = 0; i < I915_NUM_RINGS; i++)
+		I915_WRITE(RING_MAX_IDLE(dev_priv->ring[i].mmio_base), 10);
+
+	I915_WRITE(GEN6_RC_SLEEP, 0);
+	I915_WRITE(GEN6_RC1e_THRESHOLD, 1000);
+	I915_WRITE(GEN6_RC6_THRESHOLD, 50000);
+	I915_WRITE(GEN6_RC6p_THRESHOLD, 100000);
+	I915_WRITE(GEN6_RC6pp_THRESHOLD, 64000); /* unused */
+
+	I915_WRITE(GEN6_RC_CONTROL,
+		   GEN6_RC_CTL_RC6p_ENABLE |
+		   GEN6_RC_CTL_RC6_ENABLE |
+		   GEN6_RC_CTL_HW_ENABLE);
+
+	I915_WRITE(GEN6_RC_NORMAL_FREQ,
+		   GEN6_FREQUENCY(10) |
+		   GEN6_OFFSET(0) |
+		   GEN6_AGGRESSIVE_TURBO);
+	I915_WRITE(GEN6_RC_VIDEO_FREQ,
+		   GEN6_FREQUENCY(12));
+
+	I915_WRITE(GEN6_RP_DOWN_TIMEOUT, 1000000);
+	I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
+		   18 << 24 |
+		   6 << 16);
+	I915_WRITE(GEN6_RP_UP_THRESHOLD, 90000);
+	I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 100000);
+	I915_WRITE(GEN6_RP_UP_EI, 100000);
+	I915_WRITE(GEN6_RP_DOWN_EI, 300000);
+	I915_WRITE(GEN6_RP_IDLE_HYSTERSIS, 10);
+	I915_WRITE(GEN6_RP_CONTROL,
+		   GEN6_RP_MEDIA_TURBO |
+		   GEN6_RP_USE_NORMAL_FREQ |
+		   GEN6_RP_MEDIA_IS_GFX |
+		   GEN6_RP_ENABLE |
+		   GEN6_RP_UP_BUSY_MAX |
+		   GEN6_RP_DOWN_BUSY_MIN);
+
+	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
+		     500))
+		DRM_ERROR("timeout waiting for pcode mailbox to become idle\n");
+
+	I915_WRITE(GEN6_PCODE_DATA, 0);
+	I915_WRITE(GEN6_PCODE_MAILBOX,
+		   GEN6_PCODE_READY |
+		   GEN6_PCODE_WRITE_MIN_FREQ_TABLE);
+	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
+		     500))
+		DRM_ERROR("timeout waiting for pcode mailbox to finish\n");
+
+	/* requires MSI enabled */
+	I915_WRITE(GEN6_PMIER,
+		   GEN6_PM_MBOX_EVENT |
+		   GEN6_PM_THERMAL_EVENT |
+		   GEN6_PM_RP_DOWN_TIMEOUT |
+		   GEN6_PM_RP_UP_THRESHOLD |
+		   GEN6_PM_RP_DOWN_THRESHOLD |
+		   GEN6_PM_RP_UP_EI_EXPIRED |
+		   GEN6_PM_RP_DOWN_EI_EXPIRED);
+
+	__gen6_force_wake_put(dev_priv);
+}
+
 void intel_enable_clock_gating(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -5924,6 +6009,7 @@ void intel_enable_clock_gating(struct drm_device *dev)
 				   _3D_CHICKEN2_WM_READ_PIPELINED << 16 |
 				   _3D_CHICKEN2_WM_READ_PIPELINED);
 		}
+
 	} else if (IS_G4X(dev)) {
 		uint32_t dspclk_gate;
 		I915_WRITE(RENCLK_GATE_D1, 0);
@@ -5997,6 +6083,9 @@ void intel_enable_clock_gating(struct drm_device *dev)
 				   I915_READ(MCHBAR_RENDER_STANDBY) & ~RCX_SW_EXIT);
 		}
 	}
+
+	if (IS_GEN6(dev))
+		gen6_enable_rc6(dev_priv);
 }
 
 void intel_disable_clock_gating(struct drm_device *dev)