linux-kernel - Re: [PATCH v4 2/2] [media] atmel-isc: DT binding for Image Sensor Controller driver

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Date:	Sun, 12 Jun 2016 17:36:55 +0800
From:	"Wu, Songjun" <songjun.wu@...el.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:	<laurent.pinchart@...asonboard.com>, <nicolas.ferre@...el.com>,
	<alexandre.belloni@...e-electrons.com>, <robh@...nel.org>,
	<devicetree@...r.kernel.org>, Kumar Gala <galak@...eaurora.org>,
	<linux-kernel@...r.kernel.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v4 2/2] [media] atmel-isc: DT binding for Image Sensor
 Controller driver



On 6/12/2016 15:23, Boris Brezillon wrote:
> On Sun, 12 Jun 2016 11:04:27 +0800
> "Wu, Songjun" <songjun.wu@...el.com> wrote:
>
>> On 6/9/2016 05:57, Boris Brezillon wrote:
>>> On Tue, 7 Jun 2016 15:11:53 +0800
>>> Songjun Wu <songjun.wu@...el.com> wrote:
>>>
>>>> DT binding documentation for ISC driver.
>>>>
>>>> Signed-off-by: Songjun Wu <songjun.wu@...el.com>
>>>> ---
>>>>
>>>> Changes in v4:
>>>> - Remove the isc clock nodes.
>>>>
>>>> Changes in v3:
>>>> - Remove the 'atmel,sensor-preferred'.
>>>> - Modify the isc clock node according to the Rob's remarks.
>>>>
>>>> Changes in v2:
>>>> - Remove the unit address of the endpoint.
>>>> - Add the unit address to the clock node.
>>>> - Avoid using underscores in node names.
>>>> - Drop the "0x" in the unit address of the i2c node.
>>>> - Modify the description of 'atmel,sensor-preferred'.
>>>> - Add the description for the ISC internal clock.
>>>>
>>>>  .../devicetree/bindings/media/atmel-isc.txt        | 69 ++++++++++++++++++++++
>>>>  1 file changed, 69 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/media/atmel-isc.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/media/atmel-isc.txt b/Documentation/devicetree/bindings/media/atmel-isc.txt
>>>> new file mode 100644
>>>> index 0000000..3f83524
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/media/atmel-isc.txt
>>>> @@ -0,0 +1,69 @@
>>>> +Atmel Image Sensor Controller (ISC)
>>>> +----------------------------------------------
>>>> +
>>>> +Required properties for ISC:
>>>> +- compatible
>>>> +	Must be "atmel,sama5d2-isc".
>>>> +- reg
>>>> +	Physical base address and length of the registers set for the device.
>>>> +- interrupts
>>>> +	Should contain IRQ line for the ISC.
>>>> +- clocks
>>>> +	List of clock specifiers, corresponding to entries in
>>>> +	the clock-names property;
>>>> +	Please refer to clock-bindings.txt.
>>>> +- clock-names
>>>> +	Required elements: "hclock".
>>>> +- #clock-cells
>>>> +	Should be 0.
>>>> +- clock-output-names
>>>> +	Should contain the name of the clock driving the sensor master clock.
>>>> +- pinctrl-names, pinctrl-0
>>>> +	Please refer to pinctrl-bindings.txt.
>>>> +
>>>> +
>>>> +ISC supports a single port node with parallel bus. It should contain one
>>>> +'port' child node with child 'endpoint' node. Please refer to the bindings
>>>> +defined in Documentation/devicetree/bindings/media/video-interfaces.txt.
>>>> +
>>>> +Example:
>>>> +isc: isc@...08000 {
>>>> +	compatible = "atmel,sama5d2-isc";
>>>> +	reg = <0xf0008000 0x4000>;
>>>> +	interrupts = <46 IRQ_TYPE_LEVEL_HIGH 5>;
>>>> +	clocks = <&isc_clk>, <&iscck>, <&isc_gclk>;
>>>> +	clock-names = "hclock";
>>>
>>> You have 3 clocks here and only one name. Are you sure this example is
>>> actually working?
>>>
>> The isc_clk is mandatory, but the other two clocks are optional, so I
>> did not give their name. This example is tested.
>> Should I add the name for the other two clocks?
>
> It only works here because you're using these clocks as the parents of
> the ispck ismck clocks, but that's an implementation detail, and
> consumer are usually referencing their clocks by name. So yes, I'd
> recommend specifying names here, even if it's not strictly required by
> your current implementation.
>
Accept. The clock names will be specified.
Thank you.

>>
>>>> +	#clock-cells = <0>;
>>>> +	clock-output-names = "isc-mck";
>>>> +
>>>> +	port {
>>>> +		#address-cells = <1>;
>>>> +		#size-cells = <0>;
>>>> +
>>>> +		isc_0: endpoint {
>>>> +			remote-endpoint = <&ov7740_0>;
>>>> +			hsync-active = <1>;
>>>> +			vsync-active = <0>;
>>>> +			pclk-sample = <1>;
>>>> +		};
>>>> +	};
>>>> +
>>>> +
>>>> +};
>>>> +
>>>> +i2c1: i2c@...28000 {
>>>> +	ov7740: camera@21 {
>>>> +	compatible = "ovti,ov7740";
>>>> +	reg = <0x21>;
>>>> +
>>>> +	clocks = <&isc>;
>>>> +	clock-names = "xvclk";
>>>> +	assigned-clocks = <&isc>;
>>>> +	assigned-clock-rates = <24000000>;
>>>> +
>>>> +	port {
>>>> +		ov7740_0: endpoint {
>>>> +			remote-endpoint = <&isc_0>;
>>>> +		};
>>>> +	};
>>>> +};
>>>
>>>
>>>
>
>
>