On Fri, Aug 13, 2021 at 12:31:31PM +0800, Icenowy Zheng wrote:
> Currently, TCPM code omits discover when swapping to gadget, and assume
> that no altmodes are available when swapping from gadget. However, we do
> send discover when we get attached as gadget -- this leads to modes to be
> discovered twice when attached as gadget and then swap to host.
>
> Always re-send discover when swapping DR, regardless of what change is
> being made; and because of this, the assumption that no altmodes are
> registered with gadget role is broken, and altmodes de-registeration is
> always needed now.
>
> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
> ---
> drivers/usb/typec/tcpm/tcpm.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index b9bb63d749ec..ab6d0d51ee1c 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4495,15 +4495,14 @@ static void run_state_machine(struct tcpm_port *port)
> tcpm_set_state(port, ready_state(port), 0);
> break;
> case DR_SWAP_CHANGE_DR:
> - if (port->data_role == TYPEC_HOST) {
> - tcpm_unregister_altmodes(port);
> + tcpm_unregister_altmodes(port);
> + if (port->data_role == TYPEC_HOST)
> tcpm_set_roles(port, true, port->pwr_role,
> TYPEC_DEVICE);
> - } else {
> + else
> tcpm_set_roles(port, true, port->pwr_role,
> TYPEC_HOST);
> - port->send_discover = true;
> - }
> + port->send_discover = true;
> tcpm_ams_finish(port);
> tcpm_set_state(port, ready_state(port), 0);
> break;
Why is it necessary to do discovery with data role swap in general?
thanks,
--
heikki
