Re: [PATCH 01/18] staging: typec: tcpm: Add get_usb2_current_limit tcpc_dev callback

[Hans de Goede]

Hi,

On 06-08-17 16:18, Guenter Roeck wrote:
> On 08/06/2017 05:35 AM, Hans de Goede wrote:
> > A Rp signalling the default current limit indicates that we're possibly
> > connected to an USB2 power-source. In some cases the type-c
> > port-controller may provide the capability to detect the current-limit
> > for USB2 power-sources (through e.g. BC1.2 detection).
> >
> > This commit adds an optional get_usb2_current_limit tcpc_dev callback
> > which allows the port-controller to return the detected current-limit
> > if the CC pin is pulled up with Rp.
> >
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > ---
> >   drivers/staging/typec/tcpm.c | 5 ++++-
> >   drivers/staging/typec/tcpm.h | 1 +
> >   2 files changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
> > index 20eb4ebcf8c3..9f5adace4309 100644
> > --- a/drivers/staging/typec/tcpm.c
> > +++ b/drivers/staging/typec/tcpm.c
> > @@ -660,7 +660,10 @@ static u32 tcpm_get_current_limit(struct tcpm_port *port)
> >           break;
> >       case TYPEC_CC_RP_DEF:
> >       default:
> > -        limit = 0;
> > +        if (port->tcpc->get_usb2_current_limit)
>
> I think this callback should just be get_current_limit.

This is only used in the Rp-def case, which usually indicates being connected
with an A->C cable to a USB-2 device and the intend is for the callback to
implement some USB-2 specific method to detect the supported current-limit,
hence the name. If you prefer to name it just get_current_limit I can
change it for v2, but IMHO the usb2 part of the name is important as this
will not get called when USB-PD negotiation is used, nor when Rp has the Rp15
or Rp30 values.

Regards,

Hans



> > +            limit = port->tcpc->get_usb2_current_limit(port->tcpc);
> > +        else
> > +            limit = 0;
> >           break;
> >       }
> > diff --git a/drivers/staging/typec/tcpm.h b/drivers/staging/typec/tcpm.h
> > index 19c307d31a5a..01b7d89379a3 100644
> > --- a/drivers/staging/typec/tcpm.h
> > +++ b/drivers/staging/typec/tcpm.h
> > @@ -108,6 +108,7 @@ struct tcpc_dev {
> >       int (*init)(struct tcpc_dev *dev);
> >       int (*get_vbus)(struct tcpc_dev *dev);
> > +    int (*get_usb2_current_limit)(struct tcpc_dev *dev); /* Optional */
> >       int (*set_cc)(struct tcpc_dev *dev, enum typec_cc_status cc);
> >       int (*get_cc)(struct tcpc_dev *dev, enum typec_cc_status *cc1,
> >                 enum typec_cc_status *cc2);