drm/i915/cnl: apply Display WA raspberrypi#1178 to fix type C dongles

Display WA raspberrypi#1178 is meant to fix Aux channel voltage swing too low with
some type C dongles. Although it is for type C, HW engineers reported
that it can be applied to all external ports even if they are not going
to type C.

For CNL we apply the workaround every time Aux B, C and D are powering
up since they will lose the configuration when powered down.

v2: Use common tag for WA

Cc: Rodrigo Vivi <[email protected]>
Cc: Arthur J Runyan <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Signed-off-by: Lucas De Marchi <[email protected]>
Reviewed-by: Rodrigo Vivi <[email protected]>
Signed-off-by: Rodrigo Vivi <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: lucasdemarchi

drivers/gpu/drm/i915/i915_reg.h

@@ -8350,6 +8350,17 @@ enum skl_power_gate {
 #define  SKL_PW_TO_PG(pw)			((pw) - SKL_DISP_PW_1 + SKL_PG1)
 #define  SKL_FUSE_PG_DIST_STATUS(pg)		(1 << (27 - (pg)))
 
+#define _CNL_AUX_REG_IDX(pw)		((pw - 1) >> 4)
+#define _CNL_AUX_ANAOVRD1_B		0x162250
+#define _CNL_AUX_ANAOVRD1_C		0x162210
+#define _CNL_AUX_ANAOVRD1_D		0x1622D0
+#define CNL_AUX_ANAOVRD1(pw)		_MMIO(_PICK(_CNL_AUX_REG_IDX(pw), \
+						    _CNL_AUX_ANAOVRD1_B, \
+						    _CNL_AUX_ANAOVRD1_C, \
+						    _CNL_AUX_ANAOVRD1_D))
+#define   CNL_AUX_ANAOVRD1_ENABLE	(1<<16)
+#define   CNL_AUX_ANAOVRD1_LDO_BYPASS	(1<<23)
+
 /* Per-pipe DDI Function Control */
 #define _TRANS_DDI_FUNC_CTL_A		0x60400
 #define _TRANS_DDI_FUNC_CTL_B		0x61400

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -390,6 +390,15 @@ static void hsw_power_well_enable(struct drm_i915_private *dev_priv,
 	I915_WRITE(HSW_PWR_WELL_CTL_DRIVER(id), val | HSW_PWR_WELL_CTL_REQ(id));
 	hsw_wait_for_power_well_enable(dev_priv, power_well);
 
+	/* Display WA #1178: cnl */
+	if (IS_CANNONLAKE(dev_priv) &&
+	    (id == CNL_DISP_PW_AUX_B || id == CNL_DISP_PW_AUX_C ||
+	     id == CNL_DISP_PW_AUX_D)) {
+		val = I915_READ(CNL_AUX_ANAOVRD1(id));
+		val |= CNL_AUX_ANAOVRD1_ENABLE | CNL_AUX_ANAOVRD1_LDO_BYPASS;
+		I915_WRITE(CNL_AUX_ANAOVRD1(id), val);
+	}
+
 	if (wait_fuses)
 		gen9_wait_for_power_well_fuses(dev_priv, pg);