[v4,6/9] dt-bindings: display: hdmi-connector: Add DDC power supply
diff mbox series

Message ID 20190413165418.27880-7-megous@megous.com
State Changes Requested
Headers show
Series
  • Add support for Orange Pi 3
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Commit Message

Ondřej Jirman April 13, 2019, 4:54 p.m. UTC
From: Ondrej Jirman <megous@megous.com>

Some Allwinner SoC using boards (Orange Pi 3 for example) need to enable
on-board voltage shifting logic for the DDC bus to be usable. Use
ddc-supply on the hdmi-connector to model this.

Add binding documentation for optional ddc-supply property.

Signed-off-by: Ondrej Jirman <megous@megous.com>
---
 .../devicetree/bindings/display/connector/hdmi-connector.txt     | 1 +
 1 file changed, 1 insertion(+)

Comments

Rob Herring April 26, 2019, 6:23 p.m. UTC | #1
On Sat, Apr 13, 2019 at 06:54:15PM +0200, megous@megous.com wrote:
> From: Ondrej Jirman <megous@megous.com>
> 
> Some Allwinner SoC using boards (Orange Pi 3 for example) need to enable
> on-board voltage shifting logic for the DDC bus to be usable. Use
> ddc-supply on the hdmi-connector to model this.
> 
> Add binding documentation for optional ddc-supply property.
> 
> Signed-off-by: Ondrej Jirman <megous@megous.com>
> ---
>  .../devicetree/bindings/display/connector/hdmi-connector.txt     | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> index 508aee461e0d..33085aeb0bb9 100644
> --- a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> +++ b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> @@ -9,6 +9,7 @@ Optional properties:
>  - label: a symbolic name for the connector
>  - hpd-gpios: HPD GPIO number
>  - ddc-i2c-bus: phandle link to the I2C controller used for DDC EDID probing
> +- ddc-supply: the power supply for the DDC bus

It's not just for DDC. It powers the chips in bridge dongles for 
example. Pretty much every diagram I find just calls it 5V or +5V.

So how about '5V-supply' or 'v5V-supply'?

Rob
Ondřej Jirman April 26, 2019, 7:20 p.m. UTC | #2
On Fri, Apr 26, 2019 at 01:23:37PM -0500, Rob Herring wrote:
> On Sat, Apr 13, 2019 at 06:54:15PM +0200, megous@megous.com wrote:
> > From: Ondrej Jirman <megous@megous.com>
> > 
> > Some Allwinner SoC using boards (Orange Pi 3 for example) need to enable
> > on-board voltage shifting logic for the DDC bus to be usable. Use
> > ddc-supply on the hdmi-connector to model this.
> > 
> > Add binding documentation for optional ddc-supply property.
> > 
> > Signed-off-by: Ondrej Jirman <megous@megous.com>
> > ---
> >  .../devicetree/bindings/display/connector/hdmi-connector.txt     | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > index 508aee461e0d..33085aeb0bb9 100644
> > --- a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > +++ b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > @@ -9,6 +9,7 @@ Optional properties:
> >  - label: a symbolic name for the connector
> >  - hpd-gpios: HPD GPIO number
> >  - ddc-i2c-bus: phandle link to the I2C controller used for DDC EDID probing
> > +- ddc-supply: the power supply for the DDC bus
> 
> It's not just for DDC. It powers the chips in bridge dongles for 
> example. Pretty much every diagram I find just calls it 5V or +5V.
> 
> So how about '5V-supply' or 'v5V-supply'?

Just to be sure, the schematic that inspired this change looks like this:

https://megous.com/dl/tmp/33b2971de6943e9d.png

HDMI-5V is always on, and what is really being enabled here are mosfets
connected to DDC_CEC_EN and not the HDMI-5V power supply. So in this case it
really is just for DDC. It is conceivable that some boards may need both to
enable 5V for HDMI circuitry and some separate power shifting logic for
DDC bus.

So if I renamed this, the DTS would not describe the real HW very well
on Orange Pi 3.

thank you and regards,
	Ondrej

> Rob
Rob Herring April 26, 2019, 8:02 p.m. UTC | #3
On Fri, Apr 26, 2019 at 2:20 PM Ondřej Jirman <megous@megous.com> wrote:
>
> On Fri, Apr 26, 2019 at 01:23:37PM -0500, Rob Herring wrote:
> > On Sat, Apr 13, 2019 at 06:54:15PM +0200, megous@megous.com wrote:
> > > From: Ondrej Jirman <megous@megous.com>
> > >
> > > Some Allwinner SoC using boards (Orange Pi 3 for example) need to enable
> > > on-board voltage shifting logic for the DDC bus to be usable. Use
> > > ddc-supply on the hdmi-connector to model this.
> > >
> > > Add binding documentation for optional ddc-supply property.
> > >
> > > Signed-off-by: Ondrej Jirman <megous@megous.com>
> > > ---
> > >  .../devicetree/bindings/display/connector/hdmi-connector.txt     | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > index 508aee461e0d..33085aeb0bb9 100644
> > > --- a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > +++ b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > @@ -9,6 +9,7 @@ Optional properties:
> > >  - label: a symbolic name for the connector
> > >  - hpd-gpios: HPD GPIO number
> > >  - ddc-i2c-bus: phandle link to the I2C controller used for DDC EDID probing
> > > +- ddc-supply: the power supply for the DDC bus
> >
> > It's not just for DDC. It powers the chips in bridge dongles for
> > example. Pretty much every diagram I find just calls it 5V or +5V.
> >
> > So how about '5V-supply' or 'v5V-supply'?
>
> Just to be sure, the schematic that inspired this change looks like this:
>
> https://megous.com/dl/tmp/33b2971de6943e9d.png
>
> HDMI-5V is always on, and what is really being enabled here are mosfets
> connected to DDC_CEC_EN and not the HDMI-5V power supply. So in this case it
> really is just for DDC. It is conceivable that some boards may need both to
> enable 5V for HDMI circuitry and some separate power shifting logic for
> DDC bus.

Okay, not what I thought you were defining. DDC_CEC_EN is a GPIO line?
I wouldn't characterize this as a voltage rail, so I don't think it
should be a supply. Perhaps 'ddc-en-gpios'?

We certainly want to make it clear this is not the 5V supply.

Rob
Ondřej Jirman April 27, 2019, 7:01 p.m. UTC | #4
On Fri, Apr 26, 2019 at 03:02:50PM -0500, Rob Herring wrote:
> On Fri, Apr 26, 2019 at 2:20 PM Ondřej Jirman <megous@megous.com> wrote:
> >
> > On Fri, Apr 26, 2019 at 01:23:37PM -0500, Rob Herring wrote:
> > > On Sat, Apr 13, 2019 at 06:54:15PM +0200, megous@megous.com wrote:
> > > > From: Ondrej Jirman <megous@megous.com>
> > > >
> > > > Some Allwinner SoC using boards (Orange Pi 3 for example) need to enable
> > > > on-board voltage shifting logic for the DDC bus to be usable. Use
> > > > ddc-supply on the hdmi-connector to model this.
> > > >
> > > > Add binding documentation for optional ddc-supply property.
> > > >
> > > > Signed-off-by: Ondrej Jirman <megous@megous.com>
> > > > ---
> > > >  .../devicetree/bindings/display/connector/hdmi-connector.txt     | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > > index 508aee461e0d..33085aeb0bb9 100644
> > > > --- a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > > +++ b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
> > > > @@ -9,6 +9,7 @@ Optional properties:
> > > >  - label: a symbolic name for the connector
> > > >  - hpd-gpios: HPD GPIO number
> > > >  - ddc-i2c-bus: phandle link to the I2C controller used for DDC EDID probing
> > > > +- ddc-supply: the power supply for the DDC bus
> > >
> > > It's not just for DDC. It powers the chips in bridge dongles for
> > > example. Pretty much every diagram I find just calls it 5V or +5V.
> > >
> > > So how about '5V-supply' or 'v5V-supply'?
> >
> > Just to be sure, the schematic that inspired this change looks like this:
> >
> > https://megous.com/dl/tmp/33b2971de6943e9d.png
> >
> > HDMI-5V is always on, and what is really being enabled here are mosfets
> > connected to DDC_CEC_EN and not the HDMI-5V power supply. So in this case it
> > really is just for DDC. It is conceivable that some boards may need both to
> > enable 5V for HDMI circuitry and some separate power shifting logic for
> > DDC bus.
> 
> Okay, not what I thought you were defining. DDC_CEC_EN is a GPIO line?
> I wouldn't characterize this as a voltage rail, so I don't think it
> should be a supply. Perhaps 'ddc-en-gpios'?

Yes it's GPIO. I'll implement it as GPIO.

> We certainly want to make it clear this is not the 5V supply.

Right. Thank you for review.

regards,
	Ondrej

> Rob
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Patch
diff mbox series

diff --git a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
index 508aee461e0d..33085aeb0bb9 100644
--- a/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
+++ b/Documentation/devicetree/bindings/display/connector/hdmi-connector.txt
@@ -9,6 +9,7 @@  Optional properties:
 - label: a symbolic name for the connector
 - hpd-gpios: HPD GPIO number
 - ddc-i2c-bus: phandle link to the I2C controller used for DDC EDID probing
+- ddc-supply: the power supply for the DDC bus
 
 Required nodes:
 - Video port for HDMI input