On 17/09/2020 14:22, Ville Syrjälä wrote: > On Thu, Sep 17, 2020 at 08:52:10AM +0300, Tomi Valkeinen wrote: >> Add binding for DisplayPort connector. A few notes: >> >> * Similar to hdmi-connector, it has hpd-gpios as an optional property, >> as the HPD could also be handled by, e.g., the DP bridge. >> >> * dp-pwr-supply, which provides 3.3V on DP_PWR pin, is optional, as it >> is not strictly required: standard DP cables do not even have the pin >> connected. >> >> * Connector type. Full size and mini connectors are identical except for >> the connector size and form, so I believe there is no functional need >> for this property. But similar to 'label' property, it might be used >> to present information about the connector to the userspace. >> >> * No eDP. There's really no "eDP connector", as it's always a custom >> made connection between the DP and the DP panel. So possibly there is >> no need for edp-connector binding, but even if there is, I don't want >> to guess what it could look like, and could it be part of the >> dp-connector binding. >> >> * No DP++. I'm not familiar with DP++, but I think it's all handled by >> the DP bridge, and does not need any new properties to the dp-connector. > > You might need an i2c bus for this. It's up to the source device > to either hook up just AUX CH, or both AUX CH and DDC to a DP++ > connector. If just AUX CH is wired up you are limited to using > only type2 DP dual mode adapters, whereas if you also have DDC > the crappier type1 adapters will also work. Ok, thanks for the clarifications on this. > I guess it's possible some bridges might handle all that for you. > But eg. on i915 we always set up both AUX CH and DDC, and some > extra circuitry on the board will isolate one or the other > depending on what kind of dongle/cable gets plugged in > (identified via the CONFIG pins). Is that automatic on i915? I could imagine a gpio-controlled mux doing the isolation, and then we need some driver controlling the gpio. I could add the ddc bus the same way as on hdmi-connector.yaml, but perhaps it's better to leave that for someone with a DP++ board. Afaics, there should be no problems adding this later. Tomi -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
