Re: [PATCH RFC 1/8] dt-bindings: Document the hi6220 bindings for DRM driver

[Archit Taneja]

Hi,

On 09/16/2015 02:04 PM, Xinwei Kong wrote:
> hi architt
>
> On 2015/9/16 2:11, Rob Herring wrote:
> > On 09/15/2015 04:37 AM, Xinwei Kong wrote:
> > > This adds documentation of device tree bindings for the
> > > Graphics Processing Unit of hi6220 SOC.
> > >
> > > Signed-off-by: Xinliang Liu <xinliang.liu@xxxxxxxxxx>
> > > Signed-off-by: Xinwei Kong <kong.kongxinwei@xxxxxxxxxxxxx>
> > > Signed-off-by: Andy Green <andy.green@xxxxxxxxxx>
> > > Signed-off-by: Jiwen Qi <qijiwen@xxxxxxxxxxxxx>
> > > Signed-off-by: Yu Gong <gongyu@xxxxxxxxxxxxx>
> > > ---
> > >   .../devicetree/bindings/gpu/hisilicon,hi6220.txt   | 69 ++++++++++++++++++++++
> > >   1 file changed, 69 insertions(+)
> > >   create mode 100644 Documentation/devicetree/bindings/gpu/hisilicon,hi6220.txt
> > >
> > > diff --git a/Documentation/devicetree/bindings/gpu/hisilicon,hi6220.txt b/Documentation/devicetree/bindings/gpu/hisilicon,hi6220.txt
> > > new file mode 100644
> > > index 0000000..173ac63
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/gpu/hisilicon,hi6220.txt
> > > @@ -0,0 +1,69 @@
> > > + * Hisilicon hi6220 Graphics Processing Unit for HiKey board
> > > +
> > > + ** display-subsystem: Master device for binding DRM sub-components
> >
> > DRM is a Linuxism that doesn't belong in the binding.
> >
> > > +    This master device is parent node and it will be responsible to bind all
> > > +    sub-components devices node.
> >
> > Are these nodes a single block in the h/w? If not, you should describe
> > the connection of sub-nodes with of-graph instead.
> >
> > > +    - Required properties :
> > > +      - compatible: "hisilicon,display-subsystem".
> > > +      - #address-cells, #size-cells: Must be present if the device has sub-nodes.
> > > +      - ranges: to allow probing of subdevices.
> > > +      - dma-coherent: Present if dma operations are coherent.
> > > +
> > > + ** ade: Graphic overlay, Graphic post-processing, display timing control.
> > > +    This device is child node of display-subsystem
> > > +    - Required properties :
> > > +      - compatible: "hisilicon,hi6220-ade".
> > > +      - reg: physical base address of the ADE register and length of memory
> > > +	region.
> > > +      - reg-names: Should contain the reg names "ade_base" and "media_base".
> > > +      - interrupt: The interrupt number to the cpu. Defines the interrupt
> > > +        by ADE.
> > > +      - clocks: The clocks needed by the ADE module.
> > > +      - clock-names: the name of the clocks.
> > > +
> > > + ** dsi: support mipi dsi interface
> > > +    This device is child node of display-subsystem
> > > +    - Required properties :
> > > +      - compatible: "hisilicon,hi6220-dsi".
> > > +      - reg: physical base address of the DSI register and length of memory
> > > +	region.
> > > +      - clocks: The clocks needed by the DSI module.
> > > +      - clock-names: the name of the clocks.
> > > +      -	encoder-slave: phandles to a 'encoder-slave' subnode which DSI connect
> > > +        ADV7533 in order to support hdmi display.
> >
> > What the ADV7533 binding looks like is still being discussed.
> > "encoder-slave" is certainly DRM specific and not how it should be done.
> > Most likely, this needs to use the of-graph ports.
> I dont how to implement the encoder bridge stuff in upstream,
> you think that I will how to handle this part?

You can use of-graph ports to link the dsi output with the adv7533
bridge.

An example of the binding looks like:

Documentation/devicetree/bindings/drm/msm/dsi.txt

The implementation of this on the dsi host side of drm/msm
can be found in dsi_host_parse_dt, in:

drivers/gpu/drm/msm/dsi/dsi_host.c

You can get to know more about of-graph parsing here:

Documentation/devicetree/bindings/graph.txt

I'd started going through the drm/hisil patches. I'll
share more comments there.

Thanks,
Archit

> Thank you
> xinwei
>
> > Also, the ADV7533 connection is specific to HiKey. This binding should
> > just generically describe how any bridge or panel is connected.
> >
> > Rob
> >
> > .
>
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