linux-kernel - Re: [PATCH v2 1/2] dt-bindings: Document the hi6220 thermal sensor bindings

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Date:	Mon, 6 Apr 2015 21:27:28 -0700
From:	Eduardo Valentin <edubezval@...il.com>
To:	Xinwei Kong <kong.kongxinwei@...ilicon.com>
Cc:	Matt Porter <mporter@...sulko.com>, rui.zhuang@...el.com,
	mark.rutland@....com, devicetree@...r.kernel.org,
	linux-pm@...r.kernel.org, linuxarm@...wei.com,
	xuwei5@...ilicon.com, linux-kernel@...r.kernel.org,
	jorge.ramirez-ortiz@...aro.org, xweikong@...mail.com,
	liguozhu@...ilicon.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/2] dt-bindings: Document the hi6220 thermal sensor
 bindings

On Tue, Apr 07, 2015 at 11:46:22AM +0800, Xinwei Kong wrote:
> 
> 
> On 2015/4/6 22:03, Matt Porter wrote:
> > On Tue, Mar 31, 2015 at 02:59:21PM +0800, Xinwei Kong wrote:
> >> From: kongxinwei <kong.kongxinwei@...ilicon.com>
> >>
> >> This adds documentation of device tree bindings for the
> >> thermal sensor controller of hi6220 SoC.
> >>
> >> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> >> Signed-off-by: kongxinwei <kong.kongxinwei@...ilicon.com>
> >> ---
> >>  .../bindings/thermal/hisilicon-thermal.txt         | 45 ++++++++++++++++++++++
> >>  1 file changed, 45 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/thermal/hisilicon-thermal.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/thermal/hisilicon-thermal.txt b/Documentation/devicetree/bindings/thermal/hisilicon-thermal.txt
> >> new file mode 100644
> >> index 0000000..ceb6e2e
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/thermal/hisilicon-thermal.txt
> >> @@ -0,0 +1,45 @@
> >> +* Hisilicon Thermal
> >> +
> >> +This driver is for hi6220 SoC which contain 4 thermal sensor.
> >> +
> >> +	1. sensor 0: local sensor;
> >> +	2. sensor 1: remote sensor for ACPU cluster 1;
> >> +	3. sensor 2: remote sensor for ACPU cluster 2;
> >> +	4. sensor 3: remote sensor for GPU.
> >> +
> >> +Every sensor use one child node to represent it, so thermal sensor include
> >> +parent node and four child node. The parent node describe common feature and
> >> +child node describe private feature for thermal sensor;
> >> +
> >> +** Required properties :
> >> +
> >> +- compatible: "hisilicon,tsensor".
> >> +- reg: physical base address of thermal sensor and length of memory mapped
> >> +  region.
> >> +- interrupt: The interrupt number to the cpu. Defines the interrupt used
> >> +  by SOCTHERM.
> >> +- clock-names: Input clock name, should be 'thermal_clk'.
> >> +- clocks: phandles for clock specified in "clock-names" property.
> >> +- #thermal-sensor-cells: Should be 1. See ./thermal.txt for a description.
> >> +
> >> +** Required properties for child nodes :
> >> +
> >> +- hisilicon,tsensor-id: the index of thermal sensor and use it to distinguish
> >> +  thermal sensor. For example: <0> stands for local sensor; <1> stands for
> >> +  acpu1 sensor;
> > 
> > Please show an example illustrating why this property is needed. The
> > example below doesn't show any per sensor properties aside from the
> > sensor id. Other bindings with a similar sub-sensor hardware design like
> > tegra-soctherm and rockchip-thermal don't have a need for a vendor
> > specific property like this. Their drivers simply iterate over an id
> > index during thermal sensor registration.
> > 
> > -Matt
> > 
> Thermal Ip of hisilicon SoC can get four module temperature--local sensor, ACPU0
> sensor, ACPU1 sensor and gpu sensor. In order to use these sensors, this driver
> will make use of sensor id to distinguish sensor in using process.
> 
> These four sensors only get one sensor temperature at the same times. Because
> these sensor commonly use the same register by setting diff value to enable one
> sensor. howerver, sensor id is key flag for these diff sensor modules.
> 
> If deleting sensor id, this driver will define some value which set diff sensor
> regitser and it difficult to understand sensor register operation.

The above still do not explain why you need a specific property.

Could you please check
Documentation/devicetree/bindings/thermal/thermal.txt file?

There are several examples there on how to define DT nodes for the exact
case you describe above.

> 
> Thanks
> Xinwei
> 
> >> +
> >> +Example :
> >> +
> >> +	tsensor: tsensor@0,f7030700 {
> >> +		compatible = "hisilicon,tsensor";
> >> +		reg = <0x0 0xf7030700 0x0 0x1000>;
> >> +		interrupts = <0 7 0x4>;
> >> +		clocks = <&clock_sys HI6220_TSENSOR_CLK>;
> >> +		clock-names = "thermal_clk";
> >> +		#thermal-sensor-cells = <1>;
> >> +
> >> +		local_sensor {
> >> +			hisilicon,tsensor-id = <0>;
> >> +		}
> >> +		.......
> >> +	}
> >> -- 
> >> 1.9.1
> >>
> >>
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel@...ts.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > 
> > .
> > 
> 

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