drm/i915: re-enable rc6 support for Ironlake+

Re-enable rc6 support on Ironlake for power savings.  Adds a debugfs
file to check current RC state, adds a missing workaround for Ironlake
MI_SET_CONTEXT instructions, and renames MCHBAR_RENDER_STANDBY to
RSTDBYCTL to match the docs.

Keep RC6 and the power context disabled on pre-ILK.  It only seems to
hang and doesn't save any power.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -896,7 +896,7 @@ static int i915_drpc_info(struct seq_file *m, void *unused)
 	struct drm_device *dev = node->minor->dev;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	u32 rgvmodectl = I915_READ(MEMMODECTL);
-	u32 rstdbyctl = I915_READ(MCHBAR_RENDER_STANDBY);
+	u32 rstdbyctl = I915_READ(RSTDBYCTL);
 	u16 crstandvid = I915_READ16(CRSTANDVID);
 
 	seq_printf(m, "HD boost: %s\n", (rgvmodectl & MEMMODE_BOOST_EN) ?
@@ -919,6 +919,30 @@ static int i915_drpc_info(struct seq_file *m, void *unused)
 	seq_printf(m, "RS2 VID: %d\n", ((crstandvid >> 8) & 0x3f));
 	seq_printf(m, "Render standby enabled: %s\n",
 		   (rstdbyctl & RCX_SW_EXIT) ? "no" : "yes");
+	seq_printf(m, "Current RS state: ");
+	switch (rstdbyctl & RSX_STATUS_MASK) {
+	case RSX_STATUS_ON:
+		seq_printf(m, "on\n");
+		break;
+	case RSX_STATUS_RC1:
+		seq_printf(m, "RC1\n");
+		break;
+	case RSX_STATUS_RC1E:
+		seq_printf(m, "RC1E\n");
+		break;
+	case RSX_STATUS_RS1:
+		seq_printf(m, "RS1\n");
+		break;
+	case RSX_STATUS_RS2:
+		seq_printf(m, "RS2 (RC6)\n");
+		break;
+	case RSX_STATUS_RS3:
+		seq_printf(m, "RC3 (RC6+)\n");
+		break;
+	default:
+		seq_printf(m, "unknown\n");
+		break;
+	}
 
 	return 0;
 }

drivers/gpu/drm/i915/i915_reg.h

@@ -145,6 +145,8 @@
 #define   MI_END_SCENE		(1 << 4) /* flush binner and incr scene count */
 #define   MI_INVALIDATE_ISP	(1 << 5) /* invalidate indirect state pointers */
 #define MI_BATCH_BUFFER_END	MI_INSTR(0x0a, 0)
+#define MI_SUSPEND_FLUSH	MI_INSTR(0x0b, 0)
+#define   MI_SUSPEND_FLUSH_EN	(1<<0)
 #define MI_REPORT_HEAD		MI_INSTR(0x07, 0)
 #define MI_OVERLAY_FLIP		MI_INSTR(0x11,0)
 #define   MI_OVERLAY_CONTINUE	(0x0<<21)
@@ -159,6 +161,7 @@
 #define   MI_MM_SPACE_PHYSICAL		(0<<8)
 #define   MI_SAVE_EXT_STATE_EN		(1<<3)
 #define   MI_RESTORE_EXT_STATE_EN	(1<<2)
+#define   MI_FORCE_RESTORE		(1<<1)
 #define   MI_RESTORE_INHIBIT		(1<<0)
 #define MI_STORE_DWORD_IMM	MI_INSTR(0x20, 1)
 #define   MI_MEM_VIRTUAL	(1 << 22) /* 965+ only */
@@ -1131,9 +1134,50 @@
 #define RCBMINAVG		0x111a0
 #define RCUPEI			0x111b0
 #define RCDNEI			0x111b4
-#define MCHBAR_RENDER_STANDBY		0x111b8
-#define   RCX_SW_EXIT		(1<<23)
-#define   RSX_STATUS_MASK	0x00700000
+#define RSTDBYCTL		0x111b8
+#define   RS1EN			(1<<31)
+#define   RS2EN			(1<<30)
+#define   RS3EN			(1<<29)
+#define   D3RS3EN		(1<<28) /* Display D3 imlies RS3 */
+#define   SWPROMORSX		(1<<27) /* RSx promotion timers ignored */
+#define   RCWAKERW		(1<<26) /* Resetwarn from PCH causes wakeup */
+#define   DPRSLPVREN		(1<<25) /* Fast voltage ramp enable */
+#define   GFXTGHYST		(1<<24) /* Hysteresis to allow trunk gating */
+#define   RCX_SW_EXIT		(1<<23) /* Leave RSx and prevent re-entry */
+#define   RSX_STATUS_MASK	(7<<20)
+#define   RSX_STATUS_ON		(0<<20)
+#define   RSX_STATUS_RC1	(1<<20)
+#define   RSX_STATUS_RC1E	(2<<20)
+#define   RSX_STATUS_RS1	(3<<20)
+#define   RSX_STATUS_RS2	(4<<20) /* aka rc6 */
+#define   RSX_STATUS_RSVD	(5<<20) /* deep rc6 unsupported on ilk */
+#define   RSX_STATUS_RS3	(6<<20) /* rs3 unsupported on ilk */
+#define   RSX_STATUS_RSVD2	(7<<20)
+#define   UWRCRSXE		(1<<19) /* wake counter limit prevents rsx */
+#define   RSCRP			(1<<18) /* rs requests control on rs1/2 reqs */
+#define   JRSC			(1<<17) /* rsx coupled to cpu c-state */
+#define   RS2INC0		(1<<16) /* allow rs2 in cpu c0 */
+#define   RS1CONTSAV_MASK	(3<<14)
+#define   RS1CONTSAV_NO_RS1	(0<<14) /* rs1 doesn't save/restore context */
+#define   RS1CONTSAV_RSVD	(1<<14)
+#define   RS1CONTSAV_SAVE_RS1	(2<<14) /* rs1 saves context */
+#define   RS1CONTSAV_FULL_RS1	(3<<14) /* rs1 saves and restores context */
+#define   NORMSLEXLAT_MASK	(3<<12)
+#define   SLOW_RS123		(0<<12)
+#define   SLOW_RS23		(1<<12)
+#define   SLOW_RS3		(2<<12)
+#define   NORMAL_RS123		(3<<12)
+#define   RCMODE_TIMEOUT	(1<<11) /* 0 is eval interval method */
+#define   IMPROMOEN		(1<<10) /* promo is immediate or delayed until next idle interval (only for timeout method above) */
+#define   RCENTSYNC		(1<<9) /* rs coupled to cpu c-state (3/6/7) */
+#define   STATELOCK		(1<<7) /* locked to rs_cstate if 0 */
+#define   RS_CSTATE_MASK	(3<<4)
+#define   RS_CSTATE_C367_RS1	(0<<4)
+#define   RS_CSTATE_C36_RS1_C7_RS2 (1<<4)
+#define   RS_CSTATE_RSVD	(2<<4)
+#define   RS_CSTATE_C367_RS2	(3<<4)
+#define   REDSAVES		(1<<3) /* no context save if was idle during rs0 */
+#define   REDRESTORES		(1<<2) /* no restore if was idle during rs0 */
 #define VIDCTL			0x111c0
 #define VIDSTS			0x111c8
 #define VIDSTART		0x111cc /* 8 bits */

drivers/gpu/drm/i915/i915_suspend.c

@@ -740,7 +740,7 @@ void i915_restore_display(struct drm_device *dev)
 		I915_WRITE(PCH_PP_OFF_DELAYS, dev_priv->savePP_OFF_DELAYS);
 		I915_WRITE(PCH_PP_DIVISOR, dev_priv->savePP_DIVISOR);
 		I915_WRITE(PCH_PP_CONTROL, dev_priv->savePP_CONTROL);
-		I915_WRITE(MCHBAR_RENDER_STANDBY,
+		I915_WRITE(RSTDBYCTL,
 			   dev_priv->saveMCHBAR_RENDER_STANDBY);
 	} else {
 		I915_WRITE(PFIT_PGM_RATIOS, dev_priv->savePFIT_PGM_RATIOS);
@@ -811,7 +811,7 @@ int i915_save_state(struct drm_device *dev)
 		dev_priv->saveFDI_RXA_IMR = I915_READ(FDI_RXA_IMR);
 		dev_priv->saveFDI_RXB_IMR = I915_READ(FDI_RXB_IMR);
 		dev_priv->saveMCHBAR_RENDER_STANDBY =
-			I915_READ(MCHBAR_RENDER_STANDBY);
+			I915_READ(RSTDBYCTL);
 	} else {
 		dev_priv->saveIER = I915_READ(IER);
 		dev_priv->saveIMR = I915_READ(IMR);

drivers/gpu/drm/i915/intel_display.c

@@ -6420,35 +6420,37 @@ void intel_enable_clock_gating(struct drm_device *dev)
 	 * GPU can automatically power down the render unit if given a page
 	 * to save state.
 	 */
-	if (IS_IRONLAKE_M(dev) && 0) { /* XXX causes a failure during suspend */
+	if (IS_IRONLAKE_M(dev)) {
 		if (dev_priv->renderctx == NULL)
 			dev_priv->renderctx = intel_alloc_context_page(dev);
 		if (dev_priv->renderctx) {
 			struct drm_i915_gem_object *obj = dev_priv->renderctx;
-			if (BEGIN_LP_RING(4) == 0) {
-				OUT_RING(MI_SET_CONTEXT);
-				OUT_RING(obj->gtt_offset |
-					 MI_MM_SPACE_GTT |
-					 MI_SAVE_EXT_STATE_EN |
-					 MI_RESTORE_EXT_STATE_EN |
-					 MI_RESTORE_INHIBIT);
-				OUT_RING(MI_NOOP);
-				OUT_RING(MI_FLUSH);
-				ADVANCE_LP_RING();
+			if (BEGIN_LP_RING(6) != 0) {
+				i915_gem_object_unpin(obj);
+				drm_gem_object_unreference(&obj->base);
+				dev_priv->renderctx = NULL;
+				return;
 			}
+			OUT_RING(MI_SUSPEND_FLUSH | MI_SUSPEND_FLUSH_EN);
+			OUT_RING(MI_SET_CONTEXT);
+			OUT_RING(obj->gtt_offset |
+				 MI_MM_SPACE_GTT |
+				 MI_SAVE_EXT_STATE_EN |
+				 MI_RESTORE_EXT_STATE_EN |
+				 MI_RESTORE_INHIBIT);
+			OUT_RING(MI_SUSPEND_FLUSH);
+			OUT_RING(MI_NOOP);
+			OUT_RING(MI_FLUSH);
+			ADVANCE_LP_RING();
 		} else
 			DRM_DEBUG_KMS("Failed to allocate render context."
 				       "Disable RC6\n");
-	}
 
-	if (IS_GEN4(dev) && IS_MOBILE(dev)) {
 		if (dev_priv->pwrctx == NULL)
 			dev_priv->pwrctx = intel_alloc_context_page(dev);
 		if (dev_priv->pwrctx) {
 			struct drm_i915_gem_object *obj = dev_priv->pwrctx;
 			I915_WRITE(PWRCTXA, obj->gtt_offset | PWRCTX_EN);
-			I915_WRITE(MCHBAR_RENDER_STANDBY,
-				   I915_READ(MCHBAR_RENDER_STANDBY) & ~RCX_SW_EXIT);
 		}
 	}
 }