[Intel-gfx] [PATCH 1/2] drm/i915: Send a DPIO cmnreset during driver load or system resume.

[Chon Ming Lee]

Without the DPIO cmnreset, the PLL fail to lock.  This should have
done by BIOS.

v2: Move this to intel_uncore_sanitize to allow it to get call during
resume path. (Daniel)

Signed-off-by: Chon Ming Lee <chon.ming.lee at intel.com>
---
 drivers/gpu/drm/i915/intel_uncore.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 8649f1c..b1f53f3 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -276,10 +276,25 @@ static void intel_uncore_forcewake_reset(struct drm_device *dev)
 
 void intel_uncore_sanitize(struct drm_device *dev)
 {
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 reg_val;
+
 	intel_uncore_forcewake_reset(dev);
 
 	/* BIOS often leaves RC6 enabled, but disable it for hw init */
 	intel_disable_gt_powersave(dev);
+
+	/* Trigger DPIO CMN RESET, require especially in BIOS less
+	 * system
+	 */
+	if (IS_VALLEYVIEW(dev)) {
+		reg_val = I915_READ(DPIO_CTL);
+		if (!(reg_val & 0x1)) {
+			I915_WRITE(DPIO_CTL, 0x0);
+			I915_WRITE(DPIO_CTL, 0x1);
+			POSTING_READ(DPIO_CTL);
+		}
+	}
 }
 
 /*
-- 
1.7.7.6