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

[deepak.s@intel.com]

From: Deepak S <deepak.s@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 idel,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@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |  2 ++
 drivers/gpu/drm/i915/i915_reg.h |  4 +++
 drivers/gpu/drm/i915/intel_pm.c | 61 ++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1a6cc69..8c9b3a1 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -923,6 +923,8 @@ struct intel_gen6_power_mgmt {
 	bool enabled;
 	struct delayed_work delayed_resume_work;
 
+	bool gfx_clk_down;
+
 	/*
 	 * Protects RPS/RC6 register access and PCU communication.
 	 * Must be taken after struct_mutex if nested.
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1e4c693a..0a19219 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4974,6 +4974,10 @@
 						 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 e6e933b..adda054 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3581,12 +3581,70 @@ 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 clock is UP, then reset the timer as there is a possibility
+ * that normal Turbo logic can bring down the freq to Rpe.
+ * If Gfx clock is Down, 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.
+	 * Note: we use RPe here since it should match the
+	 * Vmin we were shooting for.  That should give us better
+	 * perf when we come back out of RC6 than if we used the
+	 * min freq available.
+	 */
+
+	if (dev_priv->rps.cur_delay <= dev_priv->rps.rpe_delay)
+		return;
+
+	if (!(I915_READ(VLV_GTLC_SURVIVABILITY_REG) & VLV_GFX_CLK_STATUS_BIT))
+		dev_priv->rps.gfx_clk_down = true;
+
+		/* Mask turbo interrupt so that they will not come in between */
+	if (dev_priv->rps.gfx_clk_down)
+		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 */
+	if (dev_priv->rps.gfx_clk_down)
+		I915_WRITE(GEN6_PMINTRMSK, ~GEN6_PM_RPS_EVENTS);
+
+	dev_priv->rps.gfx_clk_down = false;
+}
+
+
 void gen6_rps_idle(struct drm_i915_private *dev_priv)
 {
 	mutex_lock(&dev_priv->rps.hw_lock);
 	if (dev_priv->rps.enabled) {
 		if (dev_priv->info->is_valleyview)
-			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;
@@ -4826,6 +4884,7 @@ 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