[PATCH 4.14 106/205] usb: musb: dsps: fix otg state machine

From: Greg Kroah-Hartman
Date: Mon Feb 11 2019 - 10:27:41 EST

4.14-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@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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 dbb482b7e0ba..b7d460adaa61 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c
@@ -242,8 +242,13 @@ static int dsps_check_status(struct musb *musb, void *unused)

switch (musb->xceiv->otg->state) {
- 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 */
/* keep VBUS on for host-only mode */
if (musb->port_mode == MUSB_PORT_MODE_HOST) {