drm/i915/adlp: Add TypeC PHY TBT->DP-alt/legacy mode switch workaround

Add display workaround # 1309179469 , which fixes a PHY hang when
switching from TBT mode to DP-alt/legacy mode. The workaround also
requires an IFWI/PHY firmware change, before that this change has no
effect (the DKL_PCS_DW5/SOFTRESET flag is always cleared).

HSDES: 18018237866
HSDES: 16014473319
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220218122611.767974-1-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -3101,10 +3101,23 @@ intel_ddi_pre_pll_enable(struct intel_atomic_state *state,
 						crtc_state->lane_lat_optim_mask);
 }
 
+static void adlp_tbt_to_dp_alt_switch_wa(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
+	enum tc_port tc_port = intel_port_to_tc(i915, encoder->port);
+	int ln;
+
+	for (ln = 0; ln < 2; ln++) {
+		intel_de_write(i915, HIP_INDEX_REG(tc_port), HIP_INDEX_VAL(tc_port, ln));
+		intel_de_rmw(i915, DKL_PCS_DW5(tc_port), DKL_PCS_DW5_CORE_SOFTRESET, 0);
+	}
+}
+
 static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 					   const struct intel_crtc_state *crtc_state)
 {
-	struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *encoder = &dig_port->base;
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	enum port port = encoder->port;
 	u32 dp_tp_ctl, ddi_buf_ctl;
@@ -3140,6 +3153,10 @@ static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp,
 	intel_de_write(dev_priv, dp_tp_ctl_reg(encoder, crtc_state), dp_tp_ctl);
 	intel_de_posting_read(dev_priv, dp_tp_ctl_reg(encoder, crtc_state));
 
+	if (IS_ALDERLAKE_P(dev_priv) &&
+	    (intel_tc_port_in_dp_alt_mode(dig_port) || intel_tc_port_in_legacy_mode(dig_port)))
+		adlp_tbt_to_dp_alt_switch_wa(encoder);
+
 	intel_dp->DP |= DDI_BUF_CTL_ENABLE;
 	intel_de_write(dev_priv, DDI_BUF_CTL(port), intel_dp->DP);
 	intel_de_posting_read(dev_priv, DDI_BUF_CTL(port));

drivers/gpu/drm/i915/i915_reg.h

@@ -7914,6 +7914,12 @@ enum skl_power_gate {
 #define _DKL_PHY6_BASE			0x16D000
 
 /* DEKEL PHY MMIO Address = Phy base + (internal address & ~index_mask) */
+#define _DKL_PCS_DW5			0x14
+#define DKL_PCS_DW5(tc_port)		_MMIO(_PORT(tc_port, _DKL_PHY1_BASE, \
+						    _DKL_PHY2_BASE) + \
+						    _DKL_PCS_DW5)
+#define   DKL_PCS_DW5_CORE_SOFTRESET	REG_BIT(11)
+
 #define _DKL_PLL_DIV0			0x200
 #define   DKL_PLL_DIV0_AFC_STARTUP_MASK	REG_GENMASK(27, 25)
 #define   DKL_PLL_DIV0_AFC_STARTUP(val)	REG_FIELD_PREP(DKL_PLL_DIV0_AFC_STARTUP_MASK, (val))