Re: [PATCH v2 7/7] arm64: dts: allwinner: a64: enable ANX6345 bridge on Teres-I

[Maxime Ripard <maxime.ripard@bootlin.com>]

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On Fri, Jun 07, 2019 at 11:40:30AM +0200, Torsten Duwe wrote:
> On Fri, Jun 07, 2019 at 08:28:02AM +0200, Maxime Ripard wrote:
> > On Thu, Jun 06, 2019 at 03:59:27PM +0200, Harald Geyer wrote:
> > >
> > > If think valid compatible properties would be:
> > > compatible = "innolux,n116bge", "simple-panel";
> > > compatible = "edp-connector", "simple-panel";
> >
> > A connector isn't a panel.
> >
> > > compatible = "innolux,n116bge", "edp-connector", "simple-panel";
> >
> > And the innolux,n116bge is certainly not a connector either.
> >
> > > compatible = "edp-connector", "innolux,n116bge", "simple-panel";
> > >
> > > I can't make up my mind which one I prefere. However neither of these
> > > variants requires actually implmenting an edp-connector driver.
> >
> > No-one asked to do an edp-connector driver. You should use it in your
> > DT, but if you want to have some code in your driver that parses the
> > DT directly, I'm totally fine with that.
>
> I must admit I fail to understand what that extra node would be good for.
> Logically, the eDP far side is connected to the well-known n116bge.
> Inside the laptop case it might as well be a flat ribbon cable or
> soldered directly.
> In good intention, that's all I wanted to express in the DT. I don't
> know whether the relevant mechanical dimensions of the panel and the
> connector are standardised, so whether one could in theory assemble it
> with a different panel than the one it came with.

Because the panel that comes with the Teres-I is always the
same. However, that's not true for all the devices out there using the
bridge, starting with the pinebook.

> OTOH, as I checked during the discussion with anarsoul, the panel's
> supply voltage is permanently connected to the main 3.3V rail.

Again, that may be the case on the Teres-I, but not necessarily on
other boards.

> We already agreed that the eDP output port must not neccessarily be
> specified, this setup is a good example why: because the panel is
> always powered, the anx6345 can always pull valid EDID data from it
> so at this stage there's no need for any OS driver to reach beyond
> the bridge. IIRC even the backlight got switched off for the blank
> screen without.

That's not really the outcome of the discussion we had here though:
https://patchwork.freedesktop.org/patch/305035/

> All I wanted to say is that "there's usually an n116bge behind it";
> but this is mostly redundant.
>
> So, shall we just drop the output port specification (along with the
> panel node) in order to get one step further?

Depending on the outcome of the discussion above, yes or no :)

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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