RE: [PATCH v2 2/2] platform/chrome: cros_ec_typec: Avoid setting usb role during disconnect

[Shaikh, Azhar]

Hi Prashant,


> -----Original Message-----
> From: Prashant Malani <pmalani@xxxxxxxxxxxx>
> Sent: Wednesday, August 5, 2020 12:37 PM
> To: Shaikh, Azhar <azhar.shaikh@xxxxxxxxx>
> Cc: bleung@xxxxxxxxxxxx; enric.balletbo@xxxxxxxxxxxxx;
> groeck@xxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> heikki.krogerus@xxxxxxxxxxxxxxx; Patel, Utkarsh H
> <utkarsh.h.patel@xxxxxxxxx>; Bowman, Casey G
> <casey.g.bowman@xxxxxxxxx>; Mani, Rajmohan
> <rajmohan.mani@xxxxxxxxx>
> Subject: Re: [PATCH v2 2/2] platform/chrome: cros_ec_typec: Avoid setting
> usb role during disconnect
> 
> Hi Azhar,
> 
> 
> On Wed, Aug 5, 2020 at 12:22 PM Shaikh, Azhar <azhar.shaikh@xxxxxxxxx>
> wrote:
> >
> > Hi Prashant,
> >
> > > Is this documented anywhere? Kindly provide the links to that if so.
> > > I wasn't aware of any ordering requirements (but I may be missing
> something).
> >
> > The configuration of the connector should always happen in the order
> > defined in the USB Type-C specification. Check ch. 2.3 (USB Type-C Spec
> R2.0). So that will basically give you:
> >
> > 1. orientation
> > 2. role(s)
> > 3. the rest.
> 
> Thanks for the link. Are you referring to Section 2.3 (Configuration
> Process) ? I couldn't find anything there which implied any required ordering
> (I'm reading Release 2.0, Aug 2019, so I don't know if something has been
> added since).
> Could you kindly point me to the appropriate subsection?

That is the section I was referring to.

> 
> Additionally, I think any ordering requirements there are already handled by
> the TCPM in the Chrome OS EC.
> 
> >
> > Also I see in USB Type-C Port Manager driver the above mentioned
> > sequence being followed
> > https://elixir.bootlin.com/linux/latest/source/drivers/usb/typec/tcpm/
> > tcpm.c#L664
> 
> In addition to the above, note that this is a TCPM implementation (on
> Chrome OS the TCPM implementation is in the EC), so what is done there
> doesn't necessarily apply to cros-ec-typec.
> 
> Best regards,
> 
> -Prashant
> 
> >
> >
> > > > > -Prashant
> >
> > Regards,
> > Azhar