Re: [linux-sunxi] Re: [PATCH 02/12] drm: sun4i: Add support for enabling DDC I2C bus to dw_hdmi glue

[Ondřej Jirman <megous@xxxxxxxxxx>]

On Mon, Apr 08, 2019 at 10:47:14AM +0200, Maxime Ripard wrote:
> On Mon, Apr 08, 2019 at 03:28:24PM +0800, Chen-Yu Tsai wrote:
> > On Mon, Apr 8, 2019 at 3:23 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote:
> > >
> > > On Sat, Apr 06, 2019 at 01:45:04AM +0200, megous@xxxxxxxxxx wrote:
> > > > From: Ondrej Jirman <megous@xxxxxxxxxx>
> > > >
> > > > Orange Pi 3 board requires enabling DDC I2C bus via some GPIO connected
> > > > transistors, before it can be used. Model this as a power supply for DDC
> > > > (via regulator framework).
> > > >
> > > > Signed-off-by: Ondrej Jirman <megous@xxxxxxxxxx>
> > >
> > > The DDC bus itself is usually attached to the HDMI connector, so it
> > > would make sense to make the supply also a property of the connector.
> >
> > I believe these are separate things. What this patch covers is power for
> > a voltage shifter between the SoC and HDMI DDC pins. The HDMI connector's
> > 5V supply to power the remote DDC chip is something else. And on the
> > Orange Pi 3 they are indeed separate supplies.
> 
> Then maybe the endpoint link between the two would be the best place
> to put this?

Interestingly &hdmi node configures the DDC bus pins via pinctrl on the SoC
side, so I put this there too, because it's related to those pins. I'm not sure
if that changes anything in the discussion.

regards,
   o.

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