Re: [PATCH 1/3] staging: imx-drm: document internal HDMI I2C master controller DT binding

[Philipp Zabel <p.zabel@pengutronix.de>]

Am Montag, den 01.12.2014, 16:54 +0200 schrieb Vladimir Zapolskiy:
> Hi Philipp and Shawn,
> 
> On 15.11.2014 19:49, Vladimir Zapolskiy wrote:
> > Provide information about how to bind internal iMX6Q/DL HDMI DDC I2C
> > master controller. The property is set as optional one, because iMX6
> > HDMI DDC bus may be represented by one of general purpose I2C busses
> > found on SoC.
> > 
> > Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
> > Cc: Wolfram Sang <wsa@the-dreams.de>
> > Cc: Philipp Zabel <p.zabel@pengutronix.de>
> > Cc: Shawn Guo <shawn.guo@linaro.org>
> > Cc: devicetree@vger.kernel.org
> > Cc: linux-media@vger.kernel.org
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-i2c@vger.kernel.org
> > ---
> >  Documentation/devicetree/bindings/staging/imx-drm/hdmi.txt |   10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/staging/imx-drm/hdmi.txt b/Documentation/devicetree/bindings/staging/imx-drm/hdmi.txt
> > index 1b756cf..43c8924 100644
> > --- a/Documentation/devicetree/bindings/staging/imx-drm/hdmi.txt
> > +++ b/Documentation/devicetree/bindings/staging/imx-drm/hdmi.txt
> > @@ -10,6 +10,8 @@ Required properties:
> >   - #address-cells : should be <1>
> >   - #size-cells : should be <0>
> >   - compatible : should be "fsl,imx6q-hdmi" or "fsl,imx6dl-hdmi".
> > +   If internal HDMI DDC I2C master controller is supposed to be used,
> > +   then "simple-bus" should be added to compatible value.
> >   - gpr : should be <&gpr>.
> >     The phandle points to the iomuxc-gpr region containing the HDMI
> >     multiplexer control register.
> > @@ -22,6 +24,7 @@ Required properties:
> >  
> >  Optional properties:
> >   - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
> > + - ddc: internal HDMI DDC I2C master controller
> >  
> >  example:
> >  
> > @@ -32,7 +35,7 @@ example:
> >          hdmi: hdmi@0120000 {
> >                  #address-cells = <1>;
> >                  #size-cells = <0>;
> > -                compatible = "fsl,imx6q-hdmi";
> > +                compatible = "fsl,imx6q-hdmi", "simple-bus";
> >                  reg = <0x00120000 0x9000>;
> >                  interrupts = <0 115 0x04>;
> >                  gpr = <&gpr>;
> > @@ -40,6 +43,11 @@ example:
> >                  clock-names = "iahb", "isfr";
> >                  ddc-i2c-bus = <&i2c2>;
> >  
> > +                hdmi_ddc: ddc {
> > +                        compatible = "fsl,imx6q-hdmi-ddc";
> > +                        status = "disabled";
> > +                };
> > +
> >                  port@0 {
> >                          reg = <0>;
> >  
> > 
> 
> knowing in advance that I2C framework lacks a graceful support of non
> fully compliant I2C devices, do you have any objections to the proposed
> iMX HDMI DTS change?

I'm not sure about this. Have you seen "drm: Decouple EDID parsing from
I2C adapter"? I feel like in the absence of a ddc-i2c-bus property the
imx-hdmi/dw-hdmi driver should try to use the internal HDMI DDC I2C
master controller, bypassing the I2C framework altogether.

regards
Philipp