drm/i915: Add CHV PHY LDO power sanity checks

At various points when changing the DPIO lane/phy power states,
construct an expected value of the DISPLAY_PHY_STATUS register
and compare it with the real thing.

To construct the expected value we look at our shadow PHY_CONTROL
register value (which should match what we've just written to the
hardware), and we also need to look at the actual state of the cmn
power wells as a disabled power well causes the relevant LDO status
to be reported as 'on' in DISPLAY_PHY_STATUS.

When initially powering up the PHY it performs various internal
calibrations for which it fully powers up. That means that if we check
for the expetected power state immediately upon releasing cmnreset we
would get the occasional false positive. But we can of course
poll until the expected value appears. It shouldn't be too long so
this shouldn't make modesets substantially longer.

One extra complication is introduced when we cross the streams, ie.
drive port B with pipe B. In this case we trick CL2 (where the DPLL lives)
into life by temporaily powering up the lanes in the second channel,
and once the pipe is up and runnign we release the lane power override.
At that point the power state of CL2 has somehow gotten entangled with
the power state of the first channel. That means that constructing the
expected DISPLAY_PHY_STATUS value is a bit tricky since based on the
lane power states in the second channel, CL2 should also be powered
down. But we can use the DPLL enable bit to determine when CL2 should
be alive even if the lanes are powered down. However the power state
of CL2 isn't actually tied in with the DPLL state, but to the state
of the lanes in first channel, so we have to avoid checking the
expected state between shutting down the DPLL and powering down
the lanes in the first channel. So no calling assert_chv_phy_status()
before the DISPLAY_PHY_CONTROL write in chv_phy_powergate_lanes(),
but after the write is a safe time to check.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Deepak S <deepak.s@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -2223,6 +2223,8 @@ enum skl_disp_power_wells {
 #define   PHY_COM_LANE_RESET_DEASSERT(phy)	(1 << (phy))
 #define DISPLAY_PHY_STATUS (VLV_DISPLAY_BASE + 0x60104)
 #define   PHY_POWERGOOD(phy)	(((phy) == DPIO_PHY0) ? (1<<31) : (1<<30))
+#define   PHY_STATUS_CMN_LDO(phy, ch)                   (1 << (6-(6*(phy)+3*(ch))))
+#define   PHY_STATUS_SPLINE_LDO(phy, ch, spline)        (1 << (8-(6*(phy)+3*(ch)+(spline))))
 
 /*
  * The i830 generation, in LVDS mode, defines P1 as the bit number set within

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -958,6 +958,107 @@ static void vlv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
 	vlv_set_power_well(dev_priv, power_well, false);
 }
 
+#define POWER_DOMAIN_MASK (BIT(POWER_DOMAIN_NUM) - 1)
+
+static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv,
+						 int power_well_id)
+{
+	struct i915_power_domains *power_domains = &dev_priv->power_domains;
+	struct i915_power_well *power_well;
+	int i;
+
+	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
+		if (power_well->data == power_well_id)
+			return power_well;
+	}
+
+	return NULL;
+}
+
+#define BITS_SET(val, bits) (((val) & (bits)) == (bits))
+
+static void assert_chv_phy_status(struct drm_i915_private *dev_priv)
+{
+	struct i915_power_well *cmn_bc =
+		lookup_power_well(dev_priv, PUNIT_POWER_WELL_DPIO_CMN_BC);
+	struct i915_power_well *cmn_d =
+		lookup_power_well(dev_priv, PUNIT_POWER_WELL_DPIO_CMN_D);
+	u32 phy_control = dev_priv->chv_phy_control;
+	u32 phy_status = 0;
+	u32 tmp;
+
+	if (cmn_bc->ops->is_enabled(dev_priv, cmn_bc)) {
+		phy_status |= PHY_POWERGOOD(DPIO_PHY0);
+
+		/* this assumes override is only used to enable lanes */
+		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY0, DPIO_CH0)) == 0)
+			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH0);
+
+		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY0, DPIO_CH1)) == 0)
+			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1);
+
+		/* CL1 is on whenever anything is on in either channel */
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH0) |
+			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1)))
+			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY0, DPIO_CH0);
+
+		/*
+		 * The DPLLB check accounts for the pipe B + port A usage
+		 * with CL2 powered up but all the lanes in the second channel
+		 * powered down.
+		 */
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1)) &&
+		    (I915_READ(DPLL(PIPE_B)) & DPLL_VCO_ENABLE) == 0)
+			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY0, DPIO_CH1);
+
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY0, DPIO_CH0)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH0, 0);
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY0, DPIO_CH0)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH0, 1);
+
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY0, DPIO_CH1)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH1, 0);
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY0, DPIO_CH1)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH1, 1);
+	}
+
+	if (cmn_d->ops->is_enabled(dev_priv, cmn_d)) {
+		phy_status |= PHY_POWERGOOD(DPIO_PHY1);
+
+		/* this assumes override is only used to enable lanes */
+		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY1, DPIO_CH0)) == 0)
+			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY1, DPIO_CH0);
+
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY1, DPIO_CH0)))
+			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY1, DPIO_CH0);
+
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY1, DPIO_CH0)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY1, DPIO_CH0, 0);
+		if (BITS_SET(phy_control,
+			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY1, DPIO_CH0)))
+			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY1, DPIO_CH0, 1);
+	}
+
+	/*
+	 * The PHY may be busy with some initial calibration and whatnot,
+	 * so the power state can take a while to actually change.
+	 */
+	if (wait_for((tmp = I915_READ(DISPLAY_PHY_STATUS)) == phy_status, 10))
+		WARN(phy_status != tmp,
+		     "Unexpected PHY_STATUS 0x%08x, expected 0x%08x (PHY_CONTROL=0x%08x)\n",
+		     tmp, phy_status, dev_priv->chv_phy_control);
+}
+
+#undef BITS_SET
+
 static void chv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
 					   struct i915_power_well *power_well)
 {
@@ -1014,6 +1115,8 @@ static void chv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
 
 	DRM_DEBUG_KMS("Enabled DPIO PHY%d (PHY_CONTROL=0x%08x)\n",
 		      phy, dev_priv->chv_phy_control);
+
+	assert_chv_phy_status(dev_priv);
 }
 
 static void chv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
@@ -1040,6 +1143,8 @@ static void chv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
 
 	DRM_DEBUG_KMS("Disabled DPIO PHY%d (PHY_CONTROL=0x%08x)\n",
 		      phy, dev_priv->chv_phy_control);
+
+	assert_chv_phy_status(dev_priv);
 }
 
 static void assert_chv_phy_powergate(struct drm_i915_private *dev_priv, enum dpio_phy phy,
@@ -1117,6 +1222,8 @@ bool chv_phy_powergate_ch(struct drm_i915_private *dev_priv, enum dpio_phy phy,
 	DRM_DEBUG_KMS("Power gating DPIO PHY%d CH%d (DPIO_PHY_CONTROL=0x%08x)\n",
 		      phy, ch, dev_priv->chv_phy_control);
 
+	assert_chv_phy_status(dev_priv);
+
 out:
 	mutex_unlock(&power_domains->lock);
 
@@ -1146,6 +1253,8 @@ void chv_phy_powergate_lanes(struct intel_encoder *encoder,
 	DRM_DEBUG_KMS("Power gating DPIO PHY%d CH%d lanes 0x%x (PHY_CONTROL=0x%08x)\n",
 		      phy, ch, mask, dev_priv->chv_phy_control);
 
+	assert_chv_phy_status(dev_priv);
+
 	assert_chv_phy_powergate(dev_priv, phy, ch, override, mask);
 
 	mutex_unlock(&power_domains->lock);
@@ -1312,8 +1421,6 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	intel_runtime_pm_put(dev_priv);
 }
 
-#define POWER_DOMAIN_MASK (BIT(POWER_DOMAIN_NUM) - 1)
-
 #define HSW_ALWAYS_ON_POWER_DOMAINS (			\
 	BIT(POWER_DOMAIN_PIPE_A) |			\
 	BIT(POWER_DOMAIN_TRANSCODER_EDP) |		\
@@ -1575,21 +1682,6 @@ static struct i915_power_well chv_power_wells[] = {
 	},
 };
 
-static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv,
-						 int power_well_id)
-{
-	struct i915_power_domains *power_domains = &dev_priv->power_domains;
-	struct i915_power_well *power_well;
-	int i;
-
-	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
-		if (power_well->data == power_well_id)
-			return power_well;
-	}
-
-	return NULL;
-}
-
 bool intel_display_power_well_is_enabled(struct drm_i915_private *dev_priv,
 				    int power_well_id)
 {