From 0593265c2015227619a12a10a0600a3fe9cec549 Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Wed, 29 Sep 2021 16:28:28 +0300
Subject: drm/i915/tc: Check for DP-alt, legacy sinks before taking PHY
 ownership
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Git-commit: 30e114ef4b1620bd6768952279b53ea24e232efb
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

On ADL-P the PHY ready/complete flag is always set even in TBT-alt mode.
To avoid taking the PHY ownership and the following spurious "PHY sudden
disconnect" messages on this platform when connecting the PHY in TBT
mode, check if there is any DP-alt or legacy sink connected before
taking the ownership.

v2: (Jose)
- Fix debug message clarifying that a TBT sink can be connected.
- Add comments describing the PHY complete HW flag semantic differences
  between adl-p and other platforms.

Cc: José Roberto de Souza <jose.souza@intel.com>
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/20210929132833.2253961-2-imre.deak@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/display/intel_tc.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
index 0d3555437b0b..4e5ff823a3a3 100644
--- a/drivers/gpu/drm/i915/display/intel_tc.c
+++ b/drivers/gpu/drm/i915/display/intel_tc.c
@@ -270,6 +270,14 @@ static u32 tc_port_live_status_mask(struct intel_digital_port *dig_port)
 	return icl_tc_port_live_status_mask(dig_port);
 }
 
+/*
+ * Return the PHY status complete flag indicating that display can acquire the
+ * PHY ownership. The IOM firmware sets this flag when a DP-alt or legacy sink
+ * is connected and it's ready to switch the ownership to display. The flag
+ * will be left cleared when a TBT-alt sink is connected, where the PHY is
+ * owned by the TBT subsystem and so switching the ownership to display is not
+ * required.
+ */
 static bool icl_tc_phy_status_complete(struct intel_digital_port *dig_port)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
@@ -288,6 +296,13 @@ static bool icl_tc_phy_status_complete(struct intel_digital_port *dig_port)
 	return val & DP_PHY_MODE_STATUS_COMPLETED(dig_port->tc_phy_fia_idx);
 }
 
+/*
+ * Return the PHY status complete flag indicating that display can acquire the
+ * PHY ownership. The IOM firmware sets this flag when it's ready to switch
+ * the ownership to display, regardless of what sink is connected (TBT-alt,
+ * DP-alt, legacy or nothing). For TBT-alt sinks the PHY is owned by the TBT
+ * subsystem and so switching the ownership to display is not required.
+ */
 static bool adl_tc_phy_status_complete(struct intel_digital_port *dig_port)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
@@ -424,6 +439,7 @@ static void icl_tc_phy_connect(struct intel_digital_port *dig_port,
 			       int required_lanes)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
+	u32 live_status_mask;
 	int max_lanes;
 
 	if (!tc_phy_status_complete(dig_port)) {
@@ -432,6 +448,13 @@ static void icl_tc_phy_connect(struct intel_digital_port *dig_port,
 		goto out_set_tbt_alt_mode;
 	}
 
+	live_status_mask = tc_port_live_status_mask(dig_port);
+	if (!(live_status_mask & (BIT(TC_PORT_DP_ALT) | BIT(TC_PORT_LEGACY)))) {
+		drm_dbg_kms(&i915->drm, "Port %s: PHY ownership not required (live status %02x)\n",
+			    dig_port->tc_port_name, live_status_mask);
+		goto out_set_tbt_alt_mode;
+	}
+
 	if (!tc_phy_take_ownership(dig_port, true) &&
 	    !drm_WARN_ON(&i915->drm, dig_port->tc_legacy_port))
 		goto out_set_tbt_alt_mode;
-- 
2.38.1