Re: [v5 PATCH 1/5] extcon: Add Type-C and DP support

[Chris Zhong]

Hi Chanwoo Choi

On 07/14/2016 09:15 AM, Chanwoo Choi wrote:
> Hi Chris,
>
> [snip]
>
> > > > > Thanks,
> > > > > Chanwoo Choi
> > > > There are 4 modes for Type-C DP alt mode:
> > > > 1) USB host only  :
> > > >
> > > > extcon_set_cable_state(edev, EXTCON_USB_HOST, 1);
> > > > extcon_set_cable_state(edev, EXTCON_USB, 0);
> > > > extcon_set_cable_state(edev, EXTCON_DISP_DP, 0);
> > > >
> > > > 2) USB device only
> > > >
> > > > extcon_set_cable_state(edev, EXTCON_USB_HOST, 0);
> > > > extcon_set_cable_state(edev, EXTCON_USB, 1);
> > > > extcon_set_cable_state(edev, EXTCON_DISP_DP, 0);
> > > >
> > > > 3) DP only
> > > >
> > > > extcon_set_cable_state(edev, EXTCON_USB_HOST, 0);
> > > > extcon_set_cable_state(edev, EXTCON_USB, 0);
> > > > extcon_set_cable_state(edev, EXTCON_DISP_DP, 1);
> > > >
> > > > 4) USB + DP
> > > >
> > > > extcon_set_cable_state(edev, EXTCON_USB_HOST, 1);
> > > > extcon_set_cable_state(edev, EXTCON_USB, 0);
> > > > extcon_set_cable_state(edev, EXTCON_DISP_DP, 1);
> > > >
> > > >
> > > > for 3rd mode: DP only, there is only EXTCON_DISP_DP is attached, the EXTCON_USB_HOST
> > > > and EXTCON_USB are detached, Can I set the property into these 2 detached cable?
> > > > or just call extcon_set_cable_state(edev, EXTCON_DISP_DP, EXTCON_PROP_TYPEC_POLARITY, 0 or 1);
> > > I'm thinking to solve this issue. In result, we can add one more type to specific connector.
> > > For EXTCON_DISP_DP, we can add the two type as following. And EXTCON_PROP_TYPEC_POLARITY property
> > > should be added to EXTCON_TYPE_USB.
> > >
> > > +    [EXTCON_DISP_DP] = {
> > > +        .type = EXTCON_TYPE_DISP | EXTCON_TYPE_USB,
> > > +        .id = EXTCON_DISP_DP,
> > > +        .name = "DP",
> > > +    },
> > >
> > > So, as you mentioned, EXTCON_DISP_DP can set the EXTCON_PROP_TYPEC_POLARITY property as following:
> > > - extcon_set_cable_state(edev, EXTCON_DISP_DP, EXTCON_PROP_TYPEC_POLARITY, 0 or 1);
> > >
> > > I'll again developing the extcon property.
> > >
> > > Thanks,
> > > Chanwoo Choi
> > Nice idea, But I am thinking about is it compatible with real DisplayPort without Type-C.
> > Maybe we should add a new cable: EXTCON_DISP_DP_ALT
> >
> > +    [EXTCON_DISP_DP] = {
> > +        .type = EXTCON_TYPE_DISP,
> > +        .id = EXTCON_DISP_DP,
> > +        .name = "DP",
> > +    },
> >
> > +    [EXTCON_DISP_DP_ALT] = {
> > +        .type = EXTCON_TYPE_DISP | EXTCON_TYPE_USB,
> > +        .id = EXTCON_DISP_DP,
> > +        .name = "DP ALT",
> > +    },
> EXTCON_DISP_DP_ALT means EXTCON_DISP_DP connector with EXTCON_PROP_TYPEC_POLARITY property.
> So, we can explain the DP alternative mode without EXTCON_DISP_DP_ALT.
>
> I'm wondering to add the new EXTCON_DISP_DP_ALT connector
> because alternative mode was defined as mode instead of new h/w connector type.
>
> Thanks,
> Chanwoo Choi
Okay, so I think some comment for EXTCON_DISP_DP is necessary and enough.
>