[Intel-gfx] [PATCH 06/11] drm/i915: Wait for cdclk change to occure when going for 400MHz

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

VLV Punit doesn't support the 400MHz cdclk option, so we bypass the
Punit and poke at CCK directly. However we forgot to wait for the
frequeency change to complete. Poll the CCK clock status to make sure
the clock has changed before we fire up any pipes.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3a9b017..29dddec 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4483,6 +4483,11 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
 		val &= ~DISPLAY_FREQUENCY_VALUES;
 		val |= divider;
 		vlv_cck_write(dev_priv, CCK_DISPLAY_CLOCK_CONTROL, val);
+
+		if (wait_for((vlv_cck_read(dev_priv, CCK_DISPLAY_CLOCK_CONTROL) &
+			      DISPLAY_FREQUENCY_STATUS) == (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
+			     50))
+			DRM_ERROR("timed out waiting for CDclk change\n");
 		mutex_unlock(&dev_priv->dpio_lock);
 	}
 
-- 
1.8.5.5