Patchwork usb: musb: dsps: fix otg state machine

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Submitter Bin Liu
Date Jan. 8, 2019, 5:19 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/695093/
State New
Headers show


Bin Liu - Jan. 8, 2019, 5:19 p.m.
commit 6010abf2c2c0e382d7e8ee44bd11f343aae90cce upstream.

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.

Cc: # v4.9+
Signed-off-by: Bin Liu <>
Signed-off-by: Greg Kroah-Hartman <>
 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 4fa2456ee801..7cc94410d062 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c
@@ -244,8 +244,13 @@  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_PORT_MODE_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) {