drm/i915: Update prop, int co-eff and gain threshold for CHV

This patch implements latest PHY changes in Gain, prop and int co-efficients
based on the vco freq.

v2: Split the original changes into multiple smaller patches based on
review by Ville

v3: Addressed Ville's review comments. Fixed the error introduced in v2.
Clear the old bits before we modify those bits as part of RMW.

v4: TDC target cnt is 10 bits and not 8 bits (Ville)

Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -1041,6 +1041,8 @@ enum skl_disp_power_wells {
 
 #define _CHV_PLL_DW8_CH0		0x8020
 #define _CHV_PLL_DW8_CH1		0x81A0
+#define   DPIO_CHV_TDC_TARGET_CNT_SHIFT 0
+#define   DPIO_CHV_TDC_TARGET_CNT_MASK  (0x3FF << 0)
 #define CHV_PLL_DW8(ch) _PIPE(ch, _CHV_PLL_DW8_CH0, _CHV_PLL_DW8_CH1)
 
 #define _CHV_PLL_DW9_CH0		0x8024

drivers/gpu/drm/i915/intel_display.c

@@ -6159,18 +6159,20 @@ static void chv_prepare_pll(struct intel_crtc *crtc,
 	int pipe = crtc->pipe;
 	int dpll_reg = DPLL(crtc->pipe);
 	enum dpio_channel port = vlv_pipe_to_channel(pipe);
-	u32 loopfilter, intcoeff;
+	u32 loopfilter, tribuf_calcntr;
 	u32 bestn, bestm1, bestm2, bestp1, bestp2, bestm2_frac;
 	u32 dpio_val;
-	int refclk;
+	int vco;
 
 	bestn = pipe_config->dpll.n;
 	bestm2_frac = pipe_config->dpll.m2 & 0x3fffff;
 	bestm1 = pipe_config->dpll.m1;
 	bestm2 = pipe_config->dpll.m2 >> 22;
 	bestp1 = pipe_config->dpll.p1;
 	bestp2 = pipe_config->dpll.p2;
+	vco = pipe_config->dpll.vco;
 	dpio_val = 0;
+	loopfilter = 0;
 
 	/*
 	 * Enable Refclk and SSC
@@ -6217,18 +6219,35 @@ static void chv_prepare_pll(struct intel_crtc *crtc,
 	vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW9(port), dpio_val);
 
 	/* Loop filter */
-	refclk = i9xx_get_refclk(crtc, 0);
-	loopfilter = 5 << DPIO_CHV_PROP_COEFF_SHIFT |
-		2 << DPIO_CHV_GAIN_CTRL_SHIFT;
-	if (refclk == 100000)
-		intcoeff = 11;
-	else if (refclk == 38400)
-		intcoeff = 10;
-	else
-		intcoeff = 9;
-	loopfilter |= intcoeff << DPIO_CHV_INT_COEFF_SHIFT;
+	if (vco == 5400000) {
+		loopfilter |= (0x3 << DPIO_CHV_PROP_COEFF_SHIFT);
+		loopfilter |= (0x8 << DPIO_CHV_INT_COEFF_SHIFT);
+		loopfilter |= (0x1 << DPIO_CHV_GAIN_CTRL_SHIFT);
+		tribuf_calcntr = 0x9;
+	} else if (vco <= 6200000) {
+		loopfilter |= (0x5 << DPIO_CHV_PROP_COEFF_SHIFT);
+		loopfilter |= (0xB << DPIO_CHV_INT_COEFF_SHIFT);
+		loopfilter |= (0x3 << DPIO_CHV_GAIN_CTRL_SHIFT);
+		tribuf_calcntr = 0x9;
+	} else if (vco <= 6480000) {
+		loopfilter |= (0x4 << DPIO_CHV_PROP_COEFF_SHIFT);
+		loopfilter |= (0x9 << DPIO_CHV_INT_COEFF_SHIFT);
+		loopfilter |= (0x3 << DPIO_CHV_GAIN_CTRL_SHIFT);
+		tribuf_calcntr = 0x8;
+	} else {
+		/* Not supported. Apply the same limits as in the max case */
+		loopfilter |= (0x4 << DPIO_CHV_PROP_COEFF_SHIFT);
+		loopfilter |= (0x9 << DPIO_CHV_INT_COEFF_SHIFT);
+		loopfilter |= (0x3 << DPIO_CHV_GAIN_CTRL_SHIFT);
+		tribuf_calcntr = 0;
+	}
 	vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW6(port), loopfilter);
 
+	dpio_val = vlv_dpio_read(dev_priv, pipe, CHV_PLL_DW8(pipe));
+	dpio_val &= ~DPIO_CHV_TDC_TARGET_CNT_MASK;
+	dpio_val |= (tribuf_calcntr << DPIO_CHV_TDC_TARGET_CNT_SHIFT);
+	vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW8(port), dpio_val);
+
 	/* AFC Recal */
 	vlv_dpio_write(dev_priv, pipe, CHV_CMN_DW14(port),
 			vlv_dpio_read(dev_priv, pipe, CHV_CMN_DW14(port)) |