[PATCH 5/7] drm/i915: disable CLKOUT_DP when it's not needed

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

We currently don't support HDMI clock bending nor use SSC for DP or
HDMI on Haswell, so the only case where we need CLKOUT_DP is for VGA.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 38 ++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5f3b636..059c9a8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5305,6 +5305,36 @@ static void lpt_enable_clkout_dp(struct drm_device *dev, bool with_spread,
 	mutex_unlock(&dev_priv->dpio_lock);
 }
 
+/* Sequence to disable CLKOUT_DP */
+static void lpt_disable_clkout_dp(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	uint32_t tmp;
+
+	mutex_lock(&dev_priv->dpio_lock);
+
+	if (IS_ULT(dev_priv->dev)) {
+		tmp = intel_sbi_read(dev_priv, SBI_GEN0, SBI_ICLK);
+		tmp &= ~SBI_GEN0_ENABLE;
+		intel_sbi_write(dev_priv, SBI_GEN0, tmp, SBI_ICLK);
+	} else {
+		tmp = intel_sbi_read(dev_priv, SBI_DBUFF0, SBI_ICLK);
+		tmp &= ~SBI_DBUFF0_ENABLE;
+		intel_sbi_write(dev_priv, SBI_DBUFF0, tmp, SBI_ICLK);
+	}
+
+	tmp = intel_sbi_read(dev_priv, SBI_SSCCTL, SBI_ICLK);
+	if (!(tmp & SBI_SSCCTL_PATHALT)) {
+		tmp |= SBI_SSCCTL_PATHALT;
+		intel_sbi_write(dev_priv, SBI_SSCCTL, tmp, SBI_ICLK);
+		udelay(32);
+	}
+	tmp |= SBI_SSCCTL_DISABLE;
+	intel_sbi_write(dev_priv, SBI_SSCCTL, tmp, SBI_ICLK);
+
+	mutex_unlock(&dev_priv->dpio_lock);
+}
+
 static void lpt_init_pch_refclk(struct drm_device *dev)
 {
 	struct drm_mode_config *mode_config = &dev->mode_config;
@@ -5319,10 +5349,10 @@ static void lpt_init_pch_refclk(struct drm_device *dev)
 		}
 	}
 
-	if (!has_vga)
-		return;
-
-	lpt_enable_clkout_dp(dev, true, true);
+	if (has_vga)
+		lpt_enable_clkout_dp(dev, true, true);
+	else
+		lpt_disable_clkout_dp(dev);
 }
 
 /*
-- 
1.8.1.2