drm/i915: enable and disable PIPE_CLK_SEL at the right time

Previously we were enabling it at mode_set but never disabling. Let's
follow the mode set sequence.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e4f07a2..faa2013 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3197,6 +3197,9 @@
 		if (encoder->pre_enable)
 			encoder->pre_enable(encoder);
 
+	if (IS_HASWELL(dev))
+		intel_ddi_enable_pipe_clock(intel_crtc);
+
 	/* Enable panel fitting for LVDS */
 	if (dev_priv->pch_pf_size &&
 	    (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) || HAS_eDP)) {
@@ -3272,6 +3275,9 @@
 	I915_WRITE(PF_CTL(pipe), 0);
 	I915_WRITE(PF_WIN_SZ(pipe), 0);
 
+	if (IS_HASWELL(dev))
+		intel_ddi_disable_pipe_clock(intel_crtc);
+
 	for_each_encoder_on_crtc(dev, crtc, encoder)
 		if (encoder->post_disable)
 			encoder->post_disable(encoder);