[PATCH 1/3] phy: apple: atc: Support DUMMY PIPEHANDLER state in configure_pipehandler

[Sven Peter]

For both Thunderbolt and DisplayPort atcphy_configure_pipehandler is
reached with a request to switch to the DUMMY state (i.e. usb2 only).
With the current code this breaks USB2 when all four SS lanes are used
for DisplayPort AltMode because the -EINVAL is passed all the way back
to the phy_set_mode() call which results in tearing down xhci and dwc3
again.
Let's actually handle that case correctly and also drop the default from
the switch such that we get a compiler warning if another pipehandler
state is ever added and forgotten here.

Reported-by: Paul Cristian <p4ulcristian at gmail.com>
Closes: https://github.com/AsahiLinux/linux/pull/515
Fixes: 8e98ca1e74db ("phy: apple: Add Apple Type-C PHY")
Cc: stable at vger.kernel.org
Signed-off-by: Sven Peter <sven at kernel.org>
---
 drivers/phy/apple/atc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/phy/apple/atc.c b/drivers/phy/apple/atc.c
index 4156fabad742..a3162f25e6cd 100644
--- a/drivers/phy/apple/atc.c
+++ b/drivers/phy/apple/atc.c
@@ -1121,7 +1121,7 @@ static int atcphy_configure_pipehandler_dummy(struct apple_atcphy *atcphy)
 
 static int atcphy_configure_pipehandler(struct apple_atcphy *atcphy, bool host)
 {
-	int ret;
+	int ret = -EINVAL;
 
 	lockdep_assert_held(&atcphy->lock);
 
@@ -1136,8 +1136,10 @@ static int atcphy_configure_pipehandler(struct apple_atcphy *atcphy, bool host)
 		ret = atcphy_configure_pipehandler_dummy(atcphy);
 		atcphy->pipehandler_up = false;
 		break;
-	default:
-		ret = -EINVAL;
+	case ATCPHY_PIPEHANDLER_STATE_DUMMY:
+		ret = atcphy_configure_pipehandler_dummy(atcphy);
+		atcphy->pipehandler_up = false;
+		break;
 	}
 
 	return ret;

-- 
2.55.0