linux-kernel - [PATCH 4.19 168/313] usb: musb: dsps: fix otg state machine

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Message-Id: <20190211141904.645025754@linuxfoundation.org>
Date:   Mon, 11 Feb 2019 15:17:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bin Liu <b-liu@...com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 168/313] usb: musb: dsps: fix otg state machine

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 6010abf2c2c0e382d7e8ee44bd11f343aae90cce ]

Due to lack of ID pin interrupt event on AM335x devices, the musb dsps
driver uses polling to detect usb device attach for dual-role port.

But in the case if a micro-A cable adapter is attached without a USB device
attached to the cable, the musb state machine gets stuck in a_wait_vrise
state waiting for the MUSB_CONNECT interrupt which won't happen due to the
usb device is not attached. The state is stuck in a_wait_vrise even after
the micro-A cable is detached, which could cause VBUS retention if then the
dual-role port is attached to a host port.

To fix the problem, make a_wait_vrise as a transient state, then move the
state to either a_wait_bcon for host port or a_idle state for dual-role
port, if no usb device is attached to the port.

Signed-off-by: Bin Liu <b-liu@...com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/usb/musb/musb_dsps.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
index 23a0df79ef21..1e6d78b1334e 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c
@@ -227,8 +227,13 @@ static int dsps_check_status(struct musb *musb, void *unused)

 	switch (musb->xceiv->otg->state) {
 	case OTG_STATE_A_WAIT_VRISE:
-		dsps_mod_timer_optional(glue);
-		break;
+		if (musb->port_mode == MUSB_HOST) {
+			musb->xceiv->otg->state = OTG_STATE_A_WAIT_BCON;
+			dsps_mod_timer_optional(glue);
+			break;
+		}
+		/* fall through */
+
 	case OTG_STATE_A_WAIT_BCON:
 		/* keep VBUS on for host-only mode */
 		if (musb->port_mode == MUSB_HOST) {
-- 
2.19.1