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

From: [email-masked] (Matthias Brugger)
Date: Mon, 8 Feb 2016 18:51:31 +0100

On 22/01/16 04:38, Horng-Shyang Liao wrote:
> 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 <[email-masked]>
>>>
>>> This adds documentation for the MediaTek Global Command Engine (GCE) unit
>>> found in MT8173 SoCs.
>>>
>>> Signed-off-by: HS Liao <[email-masked]>
>>> ---
>>>   .../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.
>

The problem is that mediatek,gce is not documented, but only 
mediatek,mt8173-gce.

Regards,
Matthias