Re: [PATCH 1/4] extcon: Add USB VBUS properties

[Angus Ainslie]

Hi,

On 2020-09-14 18:40, Chanwoo Choi wrote:
> Hi,
>
> On 9/15/20 1:46 AM, Angus Ainslie wrote:
> > USB type C, USB BC1.2 and USB power delivery allow different voltages
> > and currents for VBUS so we need these additional properties.
> >
> > Also USB type C allows separate device and power roles so add a VBUS 
> > SRC
> > property.
> >
> > Signed-off-by: Angus Ainslie <angus@xxxxxxxx>
> > ---
> >  include/linux/extcon.h | 17 ++++++++++++++++-
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/extcon.h b/include/linux/extcon.h
> > index fd183fb9c20f..c4d48f4f74c4 100644
> > --- a/include/linux/extcon.h
> > +++ b/include/linux/extcon.h
> > @@ -117,14 +117,29 @@
> >   * @type:       integer (intval)
> >   * @value:      0 (USB/USB2) or 1 (USB3)
> >   * @default:    0 (USB/USB2)
> > + * - EXTCON_PROP_USB_VBUS_SRC
>
> Could you explain more correct meaning of both sink and source?

Sure I can add some comments.

> > + * @type:	integer (intval)
> > + * @value:	0 (sink) or 1 (source)
> > + * @default:	0 (sink)
> > + * - EXTCON_PROP_USB_VBUS_VOLTAGE
> > + * @type:	integer (intval)
> > + * @value:	negotiated vbus voltage in mV
> > + * @default:	5000
>
> Could you suggest the data why do you set default value as 5000?

The lowest USB VBUS is 5V so I can add that to the comments.

> > + * - EXTCON_PROP_USB_VBUS_CURRENT
> > + * @type:	integer (intval)
> > + * @value:	negotiated vbus current in mA
> > + * @default:	100
>
> ditto. Why default value is 100?

USB spec says that until the current is negotiated the max that anything 
can draw is 100mA. I can add a comment to that effect.

Thanks
Angus

> >   *
> >   */
> >  #define EXTCON_PROP_USB_VBUS		0
> >  #define EXTCON_PROP_USB_TYPEC_POLARITY	1
> >  #define EXTCON_PROP_USB_SS		2
> > +#define EXTCON_PROP_USB_VBUS_SRC	3
> > +#define EXTCON_PROP_USB_VBUS_VOLTAGE	4
> > +#define EXTCON_PROP_USB_VBUS_CURRENT	5
> >
> >  #define EXTCON_PROP_USB_MIN		0
> > -#define EXTCON_PROP_USB_MAX		2
> > +#define EXTCON_PROP_USB_MAX		5
> >  #define EXTCON_PROP_USB_CNT	(EXTCON_PROP_USB_MAX - 
> > EXTCON_PROP_USB_MIN + 1)
> >
> >  /* Properties of EXTCON_TYPE_CHG. */