Hi Guenter,
> -----Original Message-----
> From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
> Sent: Thursday, June 8, 2023 9:24 PM
> To: Xu Yang <xu.yang_2@xxxxxxx>; heikki.krogerus@xxxxxxxxxxxxxxx
> Cc: gregkh@xxxxxxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; linux-usb@xxxxxxxxxxxxxxx; Jun Li <jun.li@xxxxxxx>;
> Zhipeng Wang <zhipeng.wang_1@xxxxxxx>; Faqiang Zhu <faqiang.zhu@xxxxxxx>
> Subject: [EXT] Re: [PATCH] usb: typec: tcpci: allow drp toggling for non-drp port
>
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>
> On 6/8/23 04:28, Xu Yang wrote:
> > Some single power role Type-C port with dual data role, this kind of
> > port connects non Type-C port for usb data will need tcpm to work to
> > get polarity for orientation change and let Type-C port keep at fake
> > power role to provide another non-default data role, so remove the drp
> > port condition for now.
> >
> > Has anyone encountered this use case? How do you handle this limitation
> > in current tcpm with a better way? Please kindly share your thoughts.
> >
>
> Have you ? This is an odd comment to make in the patch description.
Sorry for this. It's not a formal patch.
>
> Either case, I don't understand why one would need to enable toggling
> under any circumstances if the port is not DRP. The description does
> not explain how "need tcpm to work" correlates to enabling toggling on
> non-DRP ports.
My case is a source-only PD capable port with dual data role, connect to
legacy PC host via A-to-C to work as USB device mode. Under current tcpm
mechanism, the PC will not recognize the source-only PD capable port and
the usb controller has no chance to work as device mode.
However, if I enable CC toggling, the PD port can re-work as sink role and
the USB controller can function as device mode too. Since it's USB3 port,
it can work only after the SS link has correctly established. Thus, we also
need tcpm to set correct orientation.
So, it seems a limitation to let single power role Type-C port with dual
data role to work as non-default data role when connected to non Type-C
port.
Thanks,
Xu Yang
>
> Guenter
>
> > Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
> > Signed-off-by: Li Jun <jun.li@xxxxxxx>
> > ---
> > drivers/usb/typec/tcpm/tcpci.c | 3 ---
> > drivers/usb/typec/tcpm/tcpm.c | 6 +++++-
> > 2 files changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> > index fc708c289a73..88559e749120 100644
> > --- a/drivers/usb/typec/tcpm/tcpci.c
> > +++ b/drivers/usb/typec/tcpm/tcpci.c
> > @@ -175,9 +175,6 @@ static int tcpci_start_toggling(struct tcpc_dev *tcpc,
> > struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> > unsigned int reg = TCPC_ROLE_CTRL_DRP;
> >
> > - if (port_type != TYPEC_PORT_DRP)
> > - return -EOPNOTSUPP;
> > -
> > /* Handle vendor drp toggling */
> > if (tcpci->data->start_drp_toggling) {
> > ret = tcpci->data->start_drp_toggling(tcpci, tcpci->data, cc);
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index 3c6b0c8e2d3a..6aa62132e69a 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -4274,7 +4274,11 @@ static void run_state_machine(struct tcpm_port *port)
> > ret = tcpm_snk_attach(port);
> > if (ret < 0)
> > tcpm_set_state(port, SNK_UNATTACHED, 0);
> > - else
> > + else if (port->port_type == TYPEC_PORT_SRC &&
> > + port->typec_caps.data == TYPEC_PORT_DRD) {
> > + tcpm_typec_connect(port);
> > + tcpm_log(port, "Keep at SNK_ATTACHED for USB data.");
> > + } else
> > tcpm_set_state(port, SNK_STARTUP, 0);
> > break;
> > case SNK_STARTUP:
