[RFC 1/3] dt-bindings: soc: Add documentation for the MediaTek GCE unit

[hs.liao@mediatek.com (Horng-Shyang Liao)]

Hi Rob,

On Wed, 2016-01-20 at 10:38 -0600, Rob Herring wrote:
> On Wed, Jan 20, 2016 at 01:14:38PM +0800, hs.liao at mediatek.com wrote:
> > From: HS Liao <hs.liao@mediatek.com>
> > 
> > This adds documentation for the MediaTek Global Command Engine (GCE) unit
> > found in MT8173 SoCs.
> > 
> > Signed-off-by: HS Liao <hs.liao@mediatek.com>
> > ---
> >  .../devicetree/bindings/soc/mediatek/gce.txt       |   33 ++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/soc/mediatek/gce.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/soc/mediatek/gce.txt b/Documentation/devicetree/bindings/soc/mediatek/gce.txt
> > new file mode 100644
> > index 0000000..878b11e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/soc/mediatek/gce.txt
> > @@ -0,0 +1,33 @@
> > +MediaTek GCE
> > +===============
> > +
> > +The Global Command Engine (GCE) is used to help read/write registers with
> > +critical time limitation, such as updating display configuration during the
> > +vblank. The GCE can be used to implement the Command Queue (CMDQ) driver.
> > +Currently, the GCE only supports display related hardwares, but we expect
> > +it can be extended to other hardwares for future requirements.
> 
> That's a hardware limitation or just s/w is only using it for display? 
> If the latter, that's not really relevant to this binding and should be 
> removed.

Just s/w is only using it for display.
I will remove it from next patch.

> > +
> > +Required properties:
> > +- compatible: Must be "mediatek,mt8173-gce"
> > +- reg: Address range of the GCE unit
> > +- interrupts: The interrupt signal from the GCE block
> > +- clock: Clocks according to the common clock binding
> > +- clock-names: Must be "gce" to stand for GCE clock
> > +
> > +Example:
> > +
> > +	gce: gce at 10212000 {
> > +		compatible = "mediatek,mt8173-gce";
> > +		reg = <0 0x10212000 0 0x1000>;
> > +		interrupts = <GIC_SPI 135 IRQ_TYPE_LEVEL_LOW>;
> > +		clocks = <&infracfg CLK_INFRA_GCE>;
> > +		clock-names = "gce";
> > +	};
> > +
> > +	mmsys: clock-controller at 14000000 {
> > +		compatible = "mediatek,mt8173-mmsys", "syscon";
> > +		reg = <0 0x14000000 0 0x1000>;
> > +		power-domains = <&scpsys MT8173_POWER_DOMAIN_MM>;
> > +		#clock-cells = <1>;
> > +		mediatek,gce = <&gce>;
> 
> Not documented.

It's just an example about how gce is used by display mmsys.
After I discussed with Mediatek display owner,
we think this can be moved to display device tree document.
Do you agree with this suggestion?
If so, I will remove it from next patch, too.

> > +	};
> > -- 
> > 1.7.9.5

Thanks,
HS Liao
> >