drm/i915: Add some CHV DPIO lane power state asserts

Add some checks that the state of the DPIO lanes is more or less what we
expect based on the overrides.

The hardware only provides two bits per channel indicating whether all
or some of the lanes are powered down, so we can't do an exact check.

Additionally, CL2 powering down before we can check it adds another
twist. To work around this we simply check for the 0 value of the
CL2 register (which is what we get when it's powered down) and
adjust our expectations.

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

@@ -1099,6 +1099,12 @@ enum skl_disp_power_wells {
 #define  DPIO_CHV_INT_LOCK_THRESHOLD_SEL_COARSE	1 /* 1: coarse & 0 : fine  */
 #define CHV_PLL_DW9(ch) _PIPE(ch, _CHV_PLL_DW9_CH0, _CHV_PLL_DW9_CH1)
 
+#define _CHV_CMN_DW0_CH0               0x8100
+#define   DPIO_ALLDL_POWERDOWN_SHIFT_CH0	19
+#define   DPIO_ANYDL_POWERDOWN_SHIFT_CH0	18
+#define   DPIO_ALLDL_POWERDOWN			(1 << 1)
+#define   DPIO_ANYDL_POWERDOWN			(1 << 0)
+
 #define _CHV_CMN_DW5_CH0               0x8114
 #define   CHV_BUFRIGHTENA1_DISABLE	(0 << 20)
 #define   CHV_BUFRIGHTENA1_NORMAL	(1 << 20)
@@ -1135,6 +1141,8 @@ enum skl_disp_power_wells {
 
 #define _CHV_CMN_DW19_CH0		0x814c
 #define _CHV_CMN_DW6_CH1		0x8098
+#define   DPIO_ALLDL_POWERDOWN_SHIFT_CH1	30 /* CL2 DW6 only */
+#define   DPIO_ANYDL_POWERDOWN_SHIFT_CH1	29 /* CL2 DW6 only */
 #define   DPIO_DYNPWRDOWNEN_CH1		(1 << 28) /* CL2 DW6 only */
 #define   CHV_CMN_USEDCLKCHANNEL	(1 << 13)
 

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -1042,6 +1042,58 @@ static void chv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
 		      phy, dev_priv->chv_phy_control);
 }
 
+static void assert_chv_phy_powergate(struct drm_i915_private *dev_priv, enum dpio_phy phy,
+				     enum dpio_channel ch, bool override, unsigned int mask)
+{
+	enum pipe pipe = phy == DPIO_PHY0 ? PIPE_A : PIPE_C;
+	u32 reg, val, expected, actual;
+
+	if (ch == DPIO_CH0)
+		reg = _CHV_CMN_DW0_CH0;
+	else
+		reg = _CHV_CMN_DW6_CH1;
+
+	mutex_lock(&dev_priv->sb_lock);
+	val = vlv_dpio_read(dev_priv, pipe, reg);
+	mutex_unlock(&dev_priv->sb_lock);
+
+	/*
+	 * This assumes !override is only used when the port is disabled.
+	 * All lanes should power down even without the override when
+	 * the port is disabled.
+	 */
+	if (!override || mask == 0xf) {
+		expected = DPIO_ALLDL_POWERDOWN | DPIO_ANYDL_POWERDOWN;
+		/*
+		 * If CH1 common lane is not active anymore
+		 * (eg. for pipe B DPLL) the entire channel will
+		 * shut down, which causes the common lane registers
+		 * to read as 0. That means we can't actually check
+		 * the lane power down status bits, but as the entire
+		 * register reads as 0 it's a good indication that the
+		 * channel is indeed entirely powered down.
+		 */
+		if (ch == DPIO_CH1 && val == 0)
+			expected = 0;
+	} else if (mask != 0x0) {
+		expected = DPIO_ANYDL_POWERDOWN;
+	} else {
+		expected = 0;
+	}
+
+	if (ch == DPIO_CH0)
+		actual = val >> DPIO_ANYDL_POWERDOWN_SHIFT_CH0;
+	else
+		actual = val >> DPIO_ANYDL_POWERDOWN_SHIFT_CH1;
+	actual &= DPIO_ALLDL_POWERDOWN | DPIO_ANYDL_POWERDOWN;
+
+	WARN(actual != expected,
+	     "Unexpected DPIO lane power down: all %d, any %d. Expected: all %d, any %d. (0x%x = 0x%08x)\n",
+	     !!(actual & DPIO_ALLDL_POWERDOWN), !!(actual & DPIO_ANYDL_POWERDOWN),
+	     !!(expected & DPIO_ALLDL_POWERDOWN), !!(expected & DPIO_ANYDL_POWERDOWN),
+	     reg, val);
+}
+
 bool chv_phy_powergate_ch(struct drm_i915_private *dev_priv, enum dpio_phy phy,
 			  enum dpio_channel ch, bool override)
 {
@@ -1094,6 +1146,8 @@ 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_powergate(dev_priv, phy, ch, override, mask);
+
 	mutex_unlock(&power_domains->lock);
 }