Hi Sasha,
On Mon, Jan 28, 2019 at 10:58:02AM -0500, Sasha Levin wrote:
> From: Bin Liu <b-liu@xxxxxx>
>
> [ 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 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,
