[Intel-gfx] [PATCH v2 2/3] drm/i915/vlv: WA to fix Voltage not getting dropped to Vmin when Gfx is power gated.

[deepak.s at intel.com]

From: Deepak S <deepak.s at intel.com>

When we enter RC6 and GFX Clocks are off, the voltage remains higher
than Vmin. When we try to set the freq to RPe, it might fail since the
Gfx clocks are down. So to fix this in Gfx idle, Bring the GFX clock up
and set the freq to RPe then move GFx down.

v2: remove vlv_update_rps_cur_delay function. Update commit message (Daniel)

Signed-off-by: Deepak S <deepak.s at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h |  4 ++++
 drivers/gpu/drm/i915/intel_pm.c | 48 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a699efd..e37831f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4940,6 +4940,10 @@
 						 GEN6_PM_RP_DOWN_THRESHOLD | \
 						 GEN6_PM_RP_DOWN_TIMEOUT)
 
+#define VLV_GTLC_SURVIVABILITY_REG              0x130098
+#define VLV_GFX_CLK_STATUS_BIT			(1<<3)
+#define VLV_GFX_CLK_FORCE_ON_BIT		(1<<2)
+
 #define GEN6_GT_GFX_RC6_LOCKED			0x138104
 #define VLV_COUNTER_CONTROL			0x138104
 #define   VLV_COUNT_RANGE_HIGH			(1<<15)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 9c950e4..a8e05fe 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3050,6 +3050,51 @@ void gen6_set_rps(struct drm_device *dev, u8 val)
 	trace_intel_gpu_freq_change(val * 50);
 }
 
+/* vlv_set_rps_idle: Set the frequency to Rpe if Gfx clocks are down
+ *
+ * * If Gfx is Idle, then
+ * 1. Mask Turbo interrupts
+ * 2. Bring up Gfx clock
+ * 3. Change the freq to Rpe and wait till P-Unit updates freq
+ * 4. Clear the Force GFX CLK ON bit so that Gfx can down
+ * 5. Unmask Turbo interrupts
+*/
+static void vlv_set_rps_idle(struct drm_i915_private *dev_priv)
+{
+	/*
+	 * When we are idle.  Drop to min voltage state.
+	 */
+
+	if (dev_priv->rps.cur_delay == dev_priv->rps.rpe_delay)
+		return;
+
+	/* Mask turbo interrupt so that they will not come in between */
+	I915_WRITE(GEN6_PMINTRMSK, 0xffffffff);
+
+	/* Bring up the Gfx clock */
+	I915_WRITE(VLV_GTLC_SURVIVABILITY_REG,
+		I915_READ(VLV_GTLC_SURVIVABILITY_REG) |
+				VLV_GFX_CLK_FORCE_ON_BIT);
+
+	if (wait_for_atomic(((VLV_GFX_CLK_STATUS_BIT &
+		I915_READ(VLV_GTLC_SURVIVABILITY_REG)) != 0), 500)) {
+			DRM_ERROR("GFX_CLK_ON request timed out\n");
+		return;
+	}
+
+	valleyview_set_rps(dev_priv->dev, dev_priv->rps.rpe_delay);
+
+	/* Release the Gfx clock */
+	I915_WRITE(VLV_GTLC_SURVIVABILITY_REG,
+		I915_READ(VLV_GTLC_SURVIVABILITY_REG) &
+				~VLV_GFX_CLK_FORCE_ON_BIT);
+
+	/* Unmask Turbo interrupts */
+	I915_WRITE(GEN6_PMINTRMSK, ~GEN6_PM_RPS_EVENTS);
+}
+
+
+
 void gen6_rps_idle(struct drm_i915_private *dev_priv)
 {
 	struct drm_device *dev = dev_priv->dev;
@@ -3057,7 +3102,7 @@ void gen6_rps_idle(struct drm_i915_private *dev_priv)
 	mutex_lock(&dev_priv->rps.hw_lock);
 	if (dev_priv->rps.enabled) {
 		if (IS_VALLEYVIEW(dev))
-			valleyview_set_rps(dev_priv->dev, dev_priv->rps.min_delay);
+			vlv_set_rps_idle(dev_priv);
 		else
 			gen6_set_rps(dev_priv->dev, dev_priv->rps.min_delay);
 		dev_priv->rps.last_adj = 0;
@@ -4288,6 +4333,7 @@ void intel_gpu_ips_teardown(void)
 	i915_mch_dev = NULL;
 	spin_unlock_irq(&mchdev_lock);
 }
+
 static void intel_init_emon(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-- 
1.8.4.2