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    Subject[PATCH AUTOSEL 4.19 176/258] usb: musb: dsps: fix otg state machine
    Date
    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) {
    --
    2.19.1
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