drm/i915/bxt: Disable DSI PLL for BXT

This patch adds two new functions:
- disable_dsi_pll.
  BXT DSI disable sequence and registers are
  different from previous platforms.
- intel_disable_dsi_pll
  wrapper function to re-use the same code for
  multiple platforms. It checks platform type and
  calls appropriate core pll disable function.

v2: Fixed Jani's review comments.

v3: Rebased on latest drm-nightly branch.
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dsi.c

@@ -557,7 +557,7 @@ static void intel_dsi_clear_device_ready(struct intel_encoder *encoder)
 		usleep_range(2000, 2500);
 	}
 
-	vlv_disable_dsi_pll(encoder);
+	intel_disable_dsi_pll(encoder);
 }
 
 static void intel_dsi_post_disable(struct intel_encoder *encoder)

drivers/gpu/drm/i915/intel_dsi.h

@@ -125,7 +125,7 @@ static inline struct intel_dsi *enc_to_intel_dsi(struct drm_encoder *encoder)
 }
 
 extern void intel_enable_dsi_pll(struct intel_encoder *encoder);
-extern void vlv_disable_dsi_pll(struct intel_encoder *encoder);
+extern void intel_disable_dsi_pll(struct intel_encoder *encoder);
 extern u32 vlv_get_dsi_pclk(struct intel_encoder *encoder, int pipe_bpp);
 
 struct drm_panel *vbt_panel_init(struct intel_dsi *intel_dsi, u16 panel_id);

drivers/gpu/drm/i915/intel_dsi_pll.c

@@ -276,7 +276,7 @@ static void vlv_enable_dsi_pll(struct intel_encoder *encoder)
 	DRM_DEBUG_KMS("DSI PLL locked\n");
 }
 
-void vlv_disable_dsi_pll(struct intel_encoder *encoder)
+static void vlv_disable_dsi_pll(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
 	u32 tmp;
@@ -293,6 +293,26 @@ void vlv_disable_dsi_pll(struct intel_encoder *encoder)
 	mutex_unlock(&dev_priv->sb_lock);
 }
 
+static void bxt_disable_dsi_pll(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = encoder->base.dev->dev_private;
+	u32 val;
+
+	DRM_DEBUG_KMS("\n");
+
+	val = I915_READ(BXT_DSI_PLL_ENABLE);
+	val &= ~BXT_DSI_PLL_DO_ENABLE;
+	I915_WRITE(BXT_DSI_PLL_ENABLE, val);
+
+	/*
+	 * PLL lock should deassert within 200us.
+	 * Wait up to 1ms before timing out.
+	 */
+	if (wait_for((I915_READ(BXT_DSI_PLL_ENABLE)
+					& BXT_DSI_PLL_LOCKED) == 0, 1))
+		DRM_ERROR("Timeout waiting for PLL lock deassertion\n");
+}
+
 static void assert_bpp_mismatch(int pixel_format, int pipe_bpp)
 {
 	int bpp = dsi_pixel_format_bpp(pixel_format);
@@ -456,3 +476,13 @@ void intel_enable_dsi_pll(struct intel_encoder *encoder)
 	else if (IS_BROXTON(dev))
 		bxt_enable_dsi_pll(encoder);
 }
+
+void intel_disable_dsi_pll(struct intel_encoder *encoder)
+{
+	struct drm_device *dev = encoder->base.dev;
+
+	if (IS_VALLEYVIEW(dev))
+		vlv_disable_dsi_pll(encoder);
+	else if (IS_BROXTON(dev))
+		bxt_disable_dsi_pll(encoder);
+}