[PATCHv2] dt-bindings: dp-connector: add binding for DisplayPort connector

[Tomi Valkeinen]

On 23/09/2020 23:00, Rob Herring wrote:
> On Wed, Sep 23, 2020 at 11:15 AM Tomi Valkeinen <tomi.valkeinen at ti.com> wrote:
>>
>> Hi Rob,
>>
>> On 23/09/2020 19:17, Rob Herring wrote:
>>
>>>> * 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.
>>>
>>> I don't think that's true. Do an image search for 'edp pinout'. AFAICT,
>>> there's 2 lane 30 pin and 4 lane 40 pin. One image says 'Table 5-3 in
>>> eDP v1.2'. Of course, I'm sure there's custom ones too. From a binding
>>> perspective, we probably don't care about the differences, but just need
>>> to be able to describe HPD, backlight power, enable, and pwm, and LCD
>>> power.
>>
>> That's true. The eDP spec lists 4 different standard pinouts (how
>> strictly those are followed, I have no idea). But it does not define a
>> connector or a cable. And afaik eDP is defined to be not user-detachable.
> 
> Yes, but HPD is still used (or sometimes broken). We could just put
> that all in panel nodes, but IIRC the last time this came up the issue
> was handling devices with different panels stuffed by the
> manufacturer. An eDP connector binding would be one way to handle that
> as it is somewhat standardized while panel connections aren't at all.

HPD in DisplayPort, and especially in eDP, is not strictly speaking "cable inserted or removed", but
rather signaling that the monitor/panel is ready (e.g. after powering it up), or there has been a
link issue, or there has been a major change in settings, or signaling DP interrupt, etc. And HPD
(and EDID and some other things) are optional with eDP.

I don't think those rule out an edp-connector, but just things to consider.

 Tomi

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