Hi Prashant,
> -----Original Message-----
> From: Prashant Malani <pmalani@xxxxxxxxxxxx>
> Sent: Thursday, November 19, 2020 12:09 AM
> To: Patel, Utkarsh H <utkarsh.h.patel@xxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> heikki.krogerus@xxxxxxxxxxxxxxx; enric.balletbo@xxxxxxxxxxxxx; Mani,
> Rajmohan <rajmohan.mani@xxxxxxxxx>; Shaikh, Azhar
> <azhar.shaikh@xxxxxxxxx>
> Subject: Re: [PATCH v3 2/4] platform/chrome: cros_ec_typec: Use Thunderbolt
> 3 cable discover mode VDO in USB4 mode
>
> Hi Utkarsh,
>
> On Wed, Nov 18, 2020 at 10:32:09PM -0800, Utkarsh Patel wrote:
> > Configure Thunderbolt 3 cable generation value by filling Thunderbolt
> > 3 cable discover mode VDO to support rounded Thunderbolt 3 cables.
> > While we are here use Thunderbolt 3 cable discover mode VDO to fill
> > active cable plug link training value.
> >
> > Suggested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> > Signed-off-by: Utkarsh Patel <utkarsh.h.patel@xxxxxxxxx>
> >
> > --
> > Changes in v3:
> > - Added a check for cable's TBT support before filling TBT3 discover mode
> > VDO.
> >
> > Changes in v2:
> > - No change.
> > --
> > ---
> > drivers/platform/chrome/cros_ec_typec.c | 14 ++++++++++++--
> > 1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/platform/chrome/cros_ec_typec.c
> > b/drivers/platform/chrome/cros_ec_typec.c
> > index 8111ed1fc574..68b17ee1d1ae 100644
> > --- a/drivers/platform/chrome/cros_ec_typec.c
> > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > @@ -514,8 +514,18 @@ static int cros_typec_enable_usb4(struct
> cros_typec_data *typec,
> > else if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_CABLE)
> > data.eudo |= EUDO_CABLE_TYPE_RE_TIMER <<
> EUDO_CABLE_TYPE_SHIFT;
> >
> > - data.active_link_training = !!(pd_ctrl->control_flags &
> > - USB_PD_CTRL_ACTIVE_LINK_UNIDIR);
> > + /*
> > + * Filling TBT3 Cable VDO when TBT3 cable is being used to establish
> > + * USB4 connection.
> > + */
> > + if (pd_ctrl->cable_gen) {
> > + data.tbt_cable_vdo = TBT_MODE;
> > +
> > + if (pd_ctrl->control_flags &
> USB_PD_CTRL_ACTIVE_LINK_UNIDIR)
> > + data.tbt_cable_vdo |= TBT_CABLE_LINK_TRAINING;
> > +
> > + data.tbt_cable_vdo |= TBT_SET_CABLE_ROUNDED(pd_ctrl-
> >cable_gen);
> > + }
>
> I think the following would decouple Rounded Support and Active Cable Link
> Training?:
Any reason you would want to decouple them?
As for the TBT3 active cable to create USB4 connection, it needs have rounded data rates.
>
> struct typec_thunderbolt_data data = {}; ...
> if (pd_ctrl->control_flags & USB_PD_CTRL_ACTIVE_LINK_UNIDIR)
> data.tbt_cable_vdo |= TBT_CABLE_LINK_TRAINING;
>
> data.tbt_cable_vdo |= TBT_SET_CABLE_ROUNDED(pd_ctrl-
> >cable_gen);
>
> if (data.tbt_cable_vdo)
> data.tbt_cable_vdo |= TBT_MODE;
>
>
> Best regards,
>
> -Prashant
Sincerely,
Utkarsh Patel.
