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.
I think from the binding perspective the connectors present in the dts
files are user-visible connectors, meant for plugging in and out. The
connector node is the "end of the chain".
And non user-detachable ones (like MIPI DPI) do not have a connector in
the dts, but just the video source and the panel linked together, and
the panel is the end of the chain.
My thinking was that eDP is similar to MIPI DPI, and that we always
define the eDP panel in the dts too. But I guess that might not be the
case, as eDP does have all the bells and whistles to fully detect the
panel. Although can it do all the probing needed for backlight and
touch... And even then, should we have a generic-epd-panel present in
the dts, or just a connector...
I don't know. So as I said, I'd rather leave eDP out for now (and you
agreed, so no disagreement =).
I think we can later extend this binding, or if eDP just doesn't seem to
fit into this, we can create a fully separate binding for eDP.
Tomi
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