drm/i915: disable CLKOUT_DP when it's not needed

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.

v2: - Replace the IS_ULT check for LPT-LP
    - Simplify GEN0/DBUFF0 check due to change on the previous patch
    - Also check for SBI_SSCCTL_DISABLE (Ben).

Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 32 insertions, 4 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 22e3f341366c..26b49d8d781c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5310,6 +5310,34 @@ 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 reg, tmp;
+
+        mutex_lock(&dev_priv->dpio_lock);
+
+        reg = (dev_priv->pch_id == INTEL_PCH_LPT_LP_DEVICE_ID_TYPE) ?
+               SBI_GEN0 : SBI_DBUFF0;
+        tmp = intel_sbi_read(dev_priv, reg, SBI_ICLK);
+        tmp &= ~SBI_GEN0_CFG_BUFFENABLE_DISABLE;
+        intel_sbi_write(dev_priv, reg, tmp, SBI_ICLK);
+
+        tmp = intel_sbi_read(dev_priv, SBI_SSCCTL, SBI_ICLK);
+        if (!(tmp & SBI_SSCCTL_DISABLE)) {
+                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;
@@ -5324,10 +5352,10 @@ 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);
 }
 
 /*