[PATCH v2] usb: typec: ucsi: Skip CAM query when partner has no alt modes

[Gris Ge <cnfourt@gmail.com>]

Since Thunderbolt alternate mode support was added,
`ucsi_altmode_update_active()` is called on every Connector Partner
Changed event.  This made the driver send `UCSI_GET_CURRENT_CAM` to
PPMs even when the partner had no alternate modes registered. Firmware
that does not support the optional alternate mode details answered Not
Supported, which produced a spurious error on every partner change:

```
ucsi_acpi USBC000:00: GET_CURRENT_CAM command failed
```

Fixed by skipping the command when there is nothing to update.

Fixes: da87d45b1951 ("usb: typec: ucsi: Add Thunderbolt alternate mode support")
Cc: stable@vger.kernel.org # v7.0+
Assisted-by: Codex:deepseek-v4.1-flash
Signed-off-by: Gris Ge <cnfourt@gmail.com>
---
v2:
  - skip the invoke of `ucsi_altmode_update_active()` in
    `ucsi_handle_connector_change()`
v1: https://lore.kernel.org/linux-usb/20260927021649.8967-1-cnfourt@gmail.com/

 drivers/usb/typec/ucsi/ucsi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index bef3f9b71d71..c392afdc27ae 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -1519,7 +1519,8 @@ static void ucsi_handle_connector_change(struct work_struct *work)

 	if (con->partner && (change & UCSI_CONSTAT_PARTNER_CHANGE)) {
 		ucsi_partner_change(con);
-		ucsi_altmode_update_active(con);
+		if (con->partner_altmode[0])
+			ucsi_altmode_update_active(con);

 		/* Complete pending data role swap */
 		if (!completion_done(&con->complete))
--
2.55.0