Hi Sasha,
On Mon, Jan 28, 2019 at 10:58:02AM -0500, Sasha Levin wrote:
From: Bin Liu b-liu@ti.com
[ 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@ti.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.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) {
This backport won't apply to stables cleanly. I have sent the manual backport [1] for v4.9+ a few weeks ago.
[1] https://marc.info/?l=linux-usb&m=154696800204159&w=2
Regards, -Bin,