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

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Thu, Oct 01, 2026 at 07:46:08AM +0800, Gris Ge wrote:
> 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>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.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

-- 
heikki