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    SubjectRe: [PATCH 2/5] usb: typec: ucsi: Check for notifications after init
    On Wed, Mar 20, 2024 at 08:39:23AM +0100, Christian A. Ehrhardt wrote:
    > The completion notification for the final SET_NOTIFICATION_ENABLE
    > command during initialization can include a connector change
    > notification. However, at the time this completion notification is
    > processed, the ucsi struct is not ready to handle this notification.
    > As a result the notification is ignored and the controller
    > never sends an interrupt again.
    >
    > Re-check CCI for a pending connector state change after
    > initialization is complete. Adjust the corresponding debug
    > message accordingly.
    >
    > Fixes: 71a1fa0df2a3 ("usb: typec: ucsi: Store the notification mask")
    > Cc: stable@vger.kernel.org
    > Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
    > ---
    > drivers/usb/typec/ucsi/ucsi.c | 10 +++++++++-
    > 1 file changed, 9 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
    > index 8a6645ffd938..dceeed207569 100644
    > --- a/drivers/usb/typec/ucsi/ucsi.c
    > +++ b/drivers/usb/typec/ucsi/ucsi.c
    > @@ -1237,7 +1237,7 @@ void ucsi_connector_change(struct ucsi *ucsi, u8 num)
    > struct ucsi_connector *con = &ucsi->connector[num - 1];
    >
    > if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
    > - dev_dbg(ucsi->dev, "Bogus connector change event\n");
    > + dev_dbg(ucsi->dev, "Early connector change event\n");
    > return;
    > }
    >
    > @@ -1636,6 +1636,7 @@ static int ucsi_init(struct ucsi *ucsi)
    > {
    > struct ucsi_connector *con, *connector;
    > u64 command, ntfy;
    > + u32 cci;
    > int ret;
    > int i;
    >
    > @@ -1688,6 +1689,13 @@ static int ucsi_init(struct ucsi *ucsi)
    >
    > ucsi->connector = connector;
    > ucsi->ntfy = ntfy;
    > +
    > + ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
    > + if (ret)
    > + return ret;
    > + if (UCSI_CCI_CONNECTOR(READ_ONCE(cci)))
    > + ucsi_connector_change(ucsi, cci);
    > +

    I think this leaves place for the race. With this patchset + "Ack
    connector change early" in place Neil triggered the following backtrace
    on sm8550 HDK while testing my UCSI-qcom-fixes patchset:
    What happens:

    [ 10.421640] write: 00000000: 05 00 e7 db 00 00 00 00

    SET_NOTIFICATION_ENABLE

    [ 10.432359] read: 00000000: 10 01 00 00 00 00 00 80 00 00 00 00 00 00 00 00
    [ 10.469553] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
    [ 10.476783] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [ 10.489552] notify: 00000000: 00 00 00 80

    COMMAND_COMPLETE

    [ 10.494194] read: 00000000: 10 01 00 00 00 00 00 80 00 00 00 00 00 00 00 00
    [ 10.501370] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
    [ 10.508578] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [ 10.515757] write: 00000000: 04 00 02 00 00 00 00 00

    ACK_CC_CI(command completed)

    [ 10.521100] read: 00000000: 10 01 00 00 00 00 00 20 00 00 00 00 00 00 00 00
    [ 10.528363] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
    [ 10.535603] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [ 10.549549] notify: 00000000: 00 00 00 20

    ACK_COMPLETE

    [Here ucsi->connector and ucsi->ntfy are being set by ucsi_init()

    [ 10.566654] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
    [ 10.593553] notify: 00000000: 02 00 00 20

    Event with CONNECTION_CHANGE. It also schedules connector_change work,
    because ucsi->ntfy is already set

    [ 10.595796] read: 00000000: 10 01 00 00 02 00 00 20 00 00 00 00 00 00 00 00
    [ 10.595798] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
    [ 10.595799] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

    The CCI read coming from ucsi_init()

    [ 10.595807] ------------[ cut here ]------------
    [ 10.595808] WARNING: CPU: 6 PID: 101 at kernel/workqueue.c:2384 __queue_work+0x374/0x474

    [skipped the register dump]

    [ 10.595953] __queue_work+0x374/0x474
    [ 10.595956] queue_work_on+0x68/0x84
    [ 10.595959] ucsi_connector_change+0x54/0x88 [typec_ucsi]
    [ 10.595963] ucsi_init_work+0x834/0x85c [typec_ucsi]
    [ 10.595968] process_one_work+0x148/0x29c
    [ 10.595971] worker_thread+0x2fc/0x40c
    [ 10.595974] kthread+0x110/0x114
    [ 10.595978] ret_from_fork+0x10/0x20
    [ 10.595985] ---[ end trace 0000000000000000 ]---

    Warning, because the work is already scheduled.


    > return 0;
    >
    > err_unregister:
    > --
    > 2.40.1
    >

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