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    Subject[PATCH v7 2/9] platform/chrome: cros_ec_typec: Purge blocking switch devlinks
    Date
    From: Prashant Malani <pmalani@chromium.org>

    When using OF graph, the fw_devlink code will create links between the
    individual port driver (cros-ec-typec here) and the parent device for
    a Type-C switch (like mode-switch). Since the mode-switch will in turn
    have the usb-c-connector (i.e the child of the port driver) as a
    supplier, fw_devlink will not be able to resolve the cyclic dependency
    correctly.

    As a result, the mode-switch driver probe() never runs, so mode-switches
    are never registered. Because of that, the port driver probe constantly
    fails with -EPROBE_DEFER, because the Type-C connector class requires all
    switch devices to be registered prior to port registration.

    To break this deadlock and allow the mode-switch registration to occur,
    purge all the usb-c-connector nodes' absent suppliers. This eliminates
    the connector as a supplier for a switch and allows it to be probed.

    Signed-off-by: Prashant Malani <pmalani@chromium.org>

    Signed-off-by: Pin-yen Lin <treapking@chromium.org>
    ---

    Changes in v7:
    - Fix the long comment lines

    Changes in v6:
    - New in v6

    drivers/platform/chrome/cros_ec_typec.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
    index 2a7ff14dc37e..30cf03c2e95d 100644
    --- a/drivers/platform/chrome/cros_ec_typec.c
    +++ b/drivers/platform/chrome/cros_ec_typec.c
    @@ -382,6 +382,16 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
    return -EINVAL;
    }

    + /*
    + * OF graph may have set up some device links with switches, since
    + * connectors have their own compatible. Purge these to avoid a deadlock
    + * in switch probe (the switch mistakenly assumes the connector is a
    + * supplier).
    + */
    + if (dev->of_node)
    + device_for_each_child_node(dev, fwnode)
    + fw_devlink_purge_absent_suppliers(fwnode);
    +
    /* DT uses "reg" to specify port number. */
    port_prop = dev->of_node ? "reg" : "port-number";
    device_for_each_child_node(dev, fwnode) {
    --
    2.39.0.314.g84b9a713c41-goog
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