drm/i915: Unify SKL cdclk init paths

Currently we initialize cdclk on SKL from two different places,
depending on whether it's during driver init or resume. Let's
unify it to happen from the same place always, and that place will be
the display core init function.

To do this we first run through the cdclk sanitation code, which will
first verify that the PLL is programmed correctly, after which we can
read out the current cdclk frequency, and once the cdclk is known we
verify that the cdclk "decimal" frequency is programmed correctly. If
any of these fail we will force a cdclk change, and to be safe we also
force the PLL to be turned off and on again. If the sanitation step
didn't notice anything amiss, we'll skip the cdclk programming which
will prevent cdclk reprogramming when the displays might be active.

We can also toss in a few WARNs about the register values into
skl_update_dpll0() since we now know that the PLL state should
always be sane when that function is called.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463172100-24715-11-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>

1 files changed, 31 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b2adb01671be..58b8d759eaaa 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5497,8 +5497,15 @@ skl_dpll0_update(struct drm_i915_private *dev_priv)
 		return;
 	}
 
+	WARN_ON((val & LCPLL_PLL_LOCK) == 0);
+
 	val = I915_READ(DPLL_CTRL1);
 
+	WARN_ON((val & (DPLL_CTRL1_HDMI_MODE(SKL_DPLL0) |
+			DPLL_CTRL1_SSC(SKL_DPLL0) |
+			DPLL_CTRL1_OVERRIDE(SKL_DPLL0))) !=
+		DPLL_CTRL1_OVERRIDE(SKL_DPLL0));
+
 	switch (val & DPLL_CTRL1_LINK_RATE_MASK(SKL_DPLL0)) {
 	case DPLL_CTRL1_LINK_RATE(DPLL_CTRL1_LINK_RATE_810, SKL_DPLL0):
 	case DPLL_CTRL1_LINK_RATE(DPLL_CTRL1_LINK_RATE_1350, SKL_DPLL0):
@@ -5668,6 +5675,8 @@ static void skl_set_cdclk(struct drm_i915_private *dev_priv, int cdclk, int vco)
 	intel_update_cdclk(dev);
 }
 
+static void skl_sanitize_cdclk(struct drm_i915_private *dev_priv);
+
 void skl_uninit_cdclk(struct drm_i915_private *dev_priv)
 {
 	/* disable DBUF power */
@@ -5684,10 +5693,19 @@ void skl_uninit_cdclk(struct drm_i915_private *dev_priv)
 
 void skl_init_cdclk(struct drm_i915_private *dev_priv)
 {
-	/* DPLL0 not enabled (happens on early BIOS versions) */
-	if (dev_priv->skl_vco_freq == 0) {
-		int cdclk, vco;
+	int cdclk, vco;
+
+	skl_sanitize_cdclk(dev_priv);
 
+	if (dev_priv->cdclk_freq != 0 && dev_priv->skl_vco_freq != 0) {
+		/*
+		 * Use the current vco as our initial
+		 * guess as to what the preferred vco is.
+		 */
+		if (dev_priv->skl_preferred_vco_freq == 0)
+			skl_set_preferred_cdclk_vco(dev_priv,
+						    dev_priv->skl_vco_freq);
+	} else {
 		/* set CDCLK to the lowest frequency, Modeset follows */
 		vco = dev_priv->skl_preferred_vco_freq;
 		if (vco == 0)
@@ -5707,7 +5725,7 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv)
 		DRM_ERROR("DBuf power enable timeout\n");
 }
 
-int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
+static void skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 {
 	uint32_t cdctl, expected;
 
@@ -5730,6 +5748,8 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 	    DPLL_CTRL1_OVERRIDE(SKL_DPLL0))
 		goto sanitize;
 
+	intel_update_cdclk(dev_priv->dev);
+
 	/* DPLL okay; verify the cdclock
 	 *
 	 * Noticed in some instances that the freq selection is correct but
@@ -5741,13 +5761,15 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
 		skl_cdclk_decimal(dev_priv->cdclk_freq);
 	if (cdctl == expected)
 		/* All well; nothing to sanitize */
-		return false;
-sanitize:
+		return;
 
-	skl_init_cdclk(dev_priv);
+sanitize:
+	DRM_DEBUG_KMS("Sanitizing cdclk programmed by pre-os\n");
 
-	/* we did have to sanitize */
-	return true;
+	/* force cdclk programming */
+	dev_priv->cdclk_freq = 0;
+	/* force full PLL disable + enable */
+	dev_priv->skl_vco_freq = -1;
 }
 
 /* Adjust CDclk dividers to allow high res or save power if possible */