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[v9,2/9] platform/chrome: cros_ec_typec: Purge blocking switch devlinks

Message ID 20230109084101.265664-3-treapking@chromium.org (mailing list archive)
State New, archived
Headers show
Series Register Type-C mode-switch in DP bridge endpoints | expand

Commit Message

Pin-yen Lin Jan. 9, 2023, 8:40 a.m. UTC 
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>

---

(no changes since v7)

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(+)

Comments

Chen-Yu Tsai Jan. 9, 2023, 9:47 a.m. UTC | #1 
On Mon, Jan 9, 2023 at 4:41 PM Pin-yen Lin <treapking@chromium.org> wrote:
>
> 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>


Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>

on MT8192 based Hayato (ASUS Chromebook Flip CM3200).
diff mbox series

Patch

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 2a7ff14dc37e..302474a647cc 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(dev))
+		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) {