[Intel-gfx] [PATCH 1/2] drm/i915: Allow GT3 Slice Shutdown on Boot.

[Rodrigo Vivi]

Slice shutdown is a power savings feature whereby parts of HW i.e. slice is
shut off on boot or dynamically to save power.

This patch only introduces a way to disable half of Haswell GT3 slices on boot.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
---
 drivers/gpu/drm/i915/i915_drv.c |  5 +++++
 drivers/gpu/drm/i915/i915_drv.h |  1 +
 drivers/gpu/drm/i915/i915_gem.c |  5 -----
 drivers/gpu/drm/i915/i915_reg.h | 11 +++++++++++
 drivers/gpu/drm/i915/intel_pm.c | 23 +++++++++++++++++++++++
 5 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 72e2be7..2650071 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -154,6 +154,11 @@ module_param_named(prefault_disable, i915_prefault_disable, bool, 0600);
 MODULE_PARM_DESC(prefault_disable,
 		"Disable page prefaulting for pread/pwrite/reloc (default:false). For developers only.");
 
+int i915_gt3_policy __read_mostly = 1;
+module_param_named(gt3_policy, i915_gt3_policy, int, 0600);
+MODULE_PARM_DESC(gt3_policy,
+		 "GT3 boot with Full (1) or Half (0) slices enabled. (default:full)");
+
 static struct drm_driver driver;
 extern int intel_agp_enabled;
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 769c138..b1c148b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1726,6 +1726,7 @@ extern bool i915_fastboot __read_mostly;
 extern int i915_enable_pc8 __read_mostly;
 extern int i915_pc8_timeout __read_mostly;
 extern bool i915_prefault_disable __read_mostly;
+extern int i915_gt3_policy __read_mostly;
 
 extern int i915_suspend(struct drm_device *dev, pm_message_t state);
 extern int i915_resume(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index fdeecae..9b13651 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4335,11 +4335,6 @@ i915_gem_init_hw(struct drm_device *dev)
 	if (dev_priv->ellc_size)
 		I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));
 
-	if (IS_HSW_GT3(dev))
-		I915_WRITE(MI_PREDICATE_RESULT_2, LOWER_SLICE_ENABLED);
-	else
-		I915_WRITE(MI_PREDICATE_RESULT_2, LOWER_SLICE_DISABLED);
-
 	if (HAS_PCH_NOP(dev)) {
 		u32 temp = I915_READ(GEN7_MSG_CTL);
 		temp &= ~(WAIT_FOR_PCH_FLR_ACK | WAIT_FOR_PCH_RESET_ACK);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index c7f2da3..c6dd502 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -269,6 +269,17 @@
 #define  LOWER_SLICE_ENABLED	(1<<0)
 #define  LOWER_SLICE_DISABLED	(0<<0)
 
+#define HSW_GT_SLICE_INFO	0x138064
+#define   SLICE_SEL_BOTH	(1<<3)
+#define   SLICE_AUTOWAKE	(1<<2)
+#define   SLICE_STATUS_MASK	0x3
+#define   SLICE_STATUS_GT_OFF	(0<<0)
+#define   SLICE_STATUS_MAIN_ON	(2<<0)
+#define   SLICE_STATUS_BOTH_ON	(3<<0)
+
+#define HSW_SLICESHUTDOWN	0xA190
+#define   SLICE_SHUTDOWN	(1<<0)
+
 /*
  * 3D instructions used by the kernel
  */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 0c115cc..5b58eee 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3617,6 +3617,28 @@ static void gen6_enable_rps(struct drm_device *dev)
 	gen6_gt_force_wake_put(dev_priv);
 }
 
+static void intel_init_gt3_slices(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (!IS_HSW_GT3(dev))
+		return;
+
+	if (!i915_gt3_policy) {
+		I915_WRITE(MI_PREDICATE_RESULT_2, LOWER_SLICE_DISABLED);
+		POSTING_READ(MI_PREDICATE_RESULT_2);
+
+		I915_WRITE(HSW_SLICESHUTDOWN, SLICE_SHUTDOWN);
+		POSTING_READ(HSW_SLICESHUTDOWN);
+
+		I915_WRITE(HSW_GT_SLICE_INFO, ~SLICE_SEL_BOTH);
+		POSTING_READ(HSW_GT_SLICE_INFO);
+	} else {
+		I915_WRITE(MI_PREDICATE_RESULT_2, LOWER_SLICE_ENABLED);
+		POSTING_READ(MI_PREDICATE_RESULT_2);
+	}
+}
+
 void gen6_update_ring_freq(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -4630,6 +4652,7 @@ static void intel_gen6_powersave_work(struct work_struct *work)
 	} else {
 		gen6_enable_rps(dev);
 		gen6_update_ring_freq(dev);
+		intel_init_gt3_slices(dev);
 	}
 	mutex_unlock(&dev_priv->rps.hw_lock);
 }
-- 
1.8.1.4