drm/i915/icl: Do read-modify-write as needed during MG PLL programming

Some MG PLL registers have fields that need to be preserved at their HW
default or BIOS programmed values. So make sure we preserve them.

v2:
- Add comment to icl_mg_pll_write() explaining the need for register
  masks. (Vandita)
- Fix patchwork checkpatch warning.

v3:
- Rebase on drm-tip.

Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: James Ausmus <james.ausmus@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: James Ausmus <james.ausmus@intel.com> (v1)
Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180619164115.7835-1-imre.deak@intel.com

drivers/gpu/drm/i915/i915_reg.h

@@ -9047,6 +9047,7 @@ enum skl_power_gate {
 #define _MG_REFCLKIN_CTL_PORT3				0x16A92C
 #define _MG_REFCLKIN_CTL_PORT4				0x16B92C
 #define   MG_REFCLKIN_CTL_OD_2_MUX(x)			((x) << 8)
+#define   MG_REFCLKIN_CTL_OD_2_MUX_MASK			(0x7 << 8)
 #define MG_REFCLKIN_CTL(port) _MMIO_PORT((port) - PORT_C, \
 					 _MG_REFCLKIN_CTL_PORT1, \
 					 _MG_REFCLKIN_CTL_PORT2)
@@ -9056,7 +9057,9 @@ enum skl_power_gate {
 #define _MG_CLKTOP2_CORECLKCTL1_PORT3			0x16A8D8
 #define _MG_CLKTOP2_CORECLKCTL1_PORT4			0x16B8D8
 #define   MG_CLKTOP2_CORECLKCTL1_B_DIVRATIO(x)		((x) << 16)
+#define   MG_CLKTOP2_CORECLKCTL1_B_DIVRATIO_MASK	(0xff << 16)
 #define   MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO(x)		((x) << 8)
+#define   MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK	(0xff << 8)
 #define MG_CLKTOP2_CORECLKCTL1(port) _MMIO_PORT((port) - PORT_C, \
 						_MG_CLKTOP2_CORECLKCTL1_PORT1, \
 						_MG_CLKTOP2_CORECLKCTL1_PORT2)
@@ -9066,9 +9069,13 @@ enum skl_power_gate {
 #define _MG_CLKTOP2_HSCLKCTL_PORT3			0x16A8D4
 #define _MG_CLKTOP2_HSCLKCTL_PORT4			0x16B8D4
 #define   MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL(x)		((x) << 16)
+#define   MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK	(0x1 << 16)
 #define   MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL(x)	((x) << 14)
+#define   MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK	(0x3 << 14)
 #define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO(x)		((x) << 12)
+#define   MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK		(0x3 << 12)
 #define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO(x)		((x) << 8)
+#define   MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK		(0xf << 8)
 #define MG_CLKTOP2_HSCLKCTL(port) _MMIO_PORT((port) - PORT_C, \
 					     _MG_CLKTOP2_HSCLKCTL_PORT1, \
 					     _MG_CLKTOP2_HSCLKCTL_PORT2)
@@ -9142,12 +9149,18 @@ enum skl_power_gate {
 #define _MG_PLL_BIAS_PORT3				0x16AA14
 #define _MG_PLL_BIAS_PORT4				0x16BA14
 #define   MG_PLL_BIAS_BIAS_GB_SEL(x)			((x) << 30)
+#define   MG_PLL_BIAS_BIAS_GB_SEL_MASK			(0x3 << 30)
 #define   MG_PLL_BIAS_INIT_DCOAMP(x)			((x) << 24)
+#define   MG_PLL_BIAS_INIT_DCOAMP_MASK			(0x3f << 24)
 #define   MG_PLL_BIAS_BIAS_BONUS(x)			((x) << 16)
+#define   MG_PLL_BIAS_BIAS_BONUS_MASK			(0xff << 16)
 #define   MG_PLL_BIAS_BIASCAL_EN			(1 << 15)
 #define   MG_PLL_BIAS_CTRIM(x)				((x) << 8)
+#define   MG_PLL_BIAS_CTRIM_MASK			(0x1f << 8)
 #define   MG_PLL_BIAS_VREF_RDAC(x)			((x) << 5)
+#define   MG_PLL_BIAS_VREF_RDAC_MASK			(0x7 << 5)
 #define   MG_PLL_BIAS_IREFTRIM(x)			((x) << 0)
+#define   MG_PLL_BIAS_IREFTRIM_MASK			(0x1f << 0)
 #define MG_PLL_BIAS(port) _MMIO_PORT((port) - PORT_C, _MG_PLL_BIAS_PORT1, \
 				     _MG_PLL_BIAS_PORT2)
 

drivers/gpu/drm/i915/intel_dpll_mgr.c

@@ -2945,10 +2945,21 @@ static bool icl_pll_get_hw_state(struct drm_i915_private *dev_priv,
 	case DPLL_ID_ICL_MGPLL4:
 		port = icl_mg_pll_id_to_port(id);
 		hw_state->mg_refclkin_ctl = I915_READ(MG_REFCLKIN_CTL(port));
+		hw_state->mg_refclkin_ctl &= MG_REFCLKIN_CTL_OD_2_MUX_MASK;
+
 		hw_state->mg_clktop2_coreclkctl1 =
 			I915_READ(MG_CLKTOP2_CORECLKCTL1(port));
+		hw_state->mg_clktop2_coreclkctl1 &=
+			MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK;
+
 		hw_state->mg_clktop2_hsclkctl =
 			I915_READ(MG_CLKTOP2_HSCLKCTL(port));
+		hw_state->mg_clktop2_hsclkctl &=
+			MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK |
+			MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK |
+			MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK |
+			MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK;
+
 		hw_state->mg_pll_div0 = I915_READ(MG_PLL_DIV0(port));
 		hw_state->mg_pll_div1 = I915_READ(MG_PLL_DIV1(port));
 		hw_state->mg_pll_lf = I915_READ(MG_PLL_LF(port));
@@ -2998,10 +3009,30 @@ static void icl_mg_pll_write(struct drm_i915_private *dev_priv,
 	enum port port = icl_mg_pll_id_to_port(pll->info->id);
 	u32 val;
 
-	I915_WRITE(MG_REFCLKIN_CTL(port), hw_state->mg_refclkin_ctl);
-	I915_WRITE(MG_CLKTOP2_CORECLKCTL1(port),
-		   hw_state->mg_clktop2_coreclkctl1);
-	I915_WRITE(MG_CLKTOP2_HSCLKCTL(port), hw_state->mg_clktop2_hsclkctl);
+	/*
+	 * Some of the following registers have reserved fields, so program
+	 * these with RMW based on a mask. The mask can be fixed or generated
+	 * during the calc/readout phase if the mask depends on some other HW
+	 * state like refclk, see icl_calc_mg_pll_state().
+	 */
+	val = I915_READ(MG_REFCLKIN_CTL(port));
+	val &= ~MG_REFCLKIN_CTL_OD_2_MUX_MASK;
+	val |= hw_state->mg_refclkin_ctl;
+	I915_WRITE(MG_REFCLKIN_CTL(port), val);
+
+	val = I915_READ(MG_CLKTOP2_CORECLKCTL1(port));
+	val &= ~MG_CLKTOP2_CORECLKCTL1_A_DIVRATIO_MASK;
+	val |= hw_state->mg_clktop2_coreclkctl1;
+	I915_WRITE(MG_CLKTOP2_CORECLKCTL1(port), val);
+
+	val = I915_READ(MG_CLKTOP2_HSCLKCTL(port));
+	val &= ~(MG_CLKTOP2_HSCLKCTL_TLINEDRV_CLKSEL_MASK |
+		 MG_CLKTOP2_HSCLKCTL_CORE_INPUTSEL_MASK |
+		 MG_CLKTOP2_HSCLKCTL_HSDIV_RATIO_MASK |
+		 MG_CLKTOP2_HSCLKCTL_DSDIV_RATIO_MASK);
+	val |= hw_state->mg_clktop2_hsclkctl;
+	I915_WRITE(MG_CLKTOP2_HSCLKCTL(port), val);
+
 	I915_WRITE(MG_PLL_DIV0(port), hw_state->mg_pll_div0);
 	I915_WRITE(MG_PLL_DIV1(port), hw_state->mg_pll_div1);
 	I915_WRITE(MG_PLL_LF(port), hw_state->mg_pll_lf);