linux-kernel - Re: [PATCH v4 5/5] usb: dwc3: rockchip: add devicetree bindings documentation

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Message-ID: <5763C083.2030304@rock-chips.com>
Date:	Fri, 17 Jun 2016 17:18:59 +0800
From:	William Wu <william.wu@...k-chips.com>
To:	Heiko Stübner <heiko@...ech.de>
CC:	gregkh@...uxfoundation.org, balbi@...nel.org,
	linux-rockchip@...ts.infradead.org, briannorris@...gle.com,
	dianders@...gle.com, kever.yang@...k-chips.com,
	huangtao@...k-chips.com, frank.wang@...k-chips.com,
	eddie.cai@...k-chips.com, John.Youn@...opsys.com,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v4 5/5] usb: dwc3: rockchip: add devicetree bindings documentation

Dear Heiko,

On 06/17/2016 07:15 AM, Heiko Stübner wrote:
> Hi William,
>
> Am Donnerstag, 2. Juni 2016, 20:34:56 schrieb William Wu:
>> This patch adds the devicetree documentation required for Rockchip
>> USB3.0 core wrapper consisting of USB3.0 IP from Synopsys.
>>
>> It supports DRD mode, and could operate in device mode (SS, HS, FS)
>> and host mode (SS, HS, FS, LS).
>>
>> Signed-off-by: William Wu <william.wu@...k-chips.com>
> devicetree binding documentation patches should include the devicetree
> maintainers (scripts/get_maintainer.pl)
I'll add devicetree maintainers in next patch v5.
>
>> ---
>> Changes in v4:
>> - modify commit log, and add phy documentation location (Sergei)
>>
>> Changes in v3:
>> - add dwc3 address (balbi)
>>
>> Changes in v2:
>> - add rockchip,dwc3.txt to Documentation/devicetree/bindings/ (balbi,
> Brian)
>>   .../devicetree/bindings/usb/rockchip,dwc3.txt      | 46
>> ++++++++++++++++++++++ 1 file changed, 46 insertions(+)
>>   create mode 100644
> Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
>> diff --git a/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
>> b/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt new file mode
>> 100644
>> index 0000000..0edf013
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/usb/rockchip,dwc3.txt
>> @@ -0,0 +1,46 @@
>> +Rockchip SuperSpeed DWC3 USB SoC controller
>> +
>> +Required properties:
>> +- compatible:	should contain "rockchip,dwc3"
> are you sure this will work for all future socs in the same way? I guess
> doing this as rockchip,rk3399-dwc3 might make our lifes easier down the road
> :-) [both the xilinx and st dwc3 bindings do already that]
I'm not sure that whether our future socs dwc3 will work well in the 
same way.
So I think "rockchip,rk3399-dwc3" is more appropriate.
Thanks very much for your suggestion.
>
>> +- clocks:		A list of phandle + clock-specifier pairs for the
>> +				clocks listed in clock-names
>> +- clock-names:	Should contain the following:
>> +  "clk_usb3otg0_ref"	Controller reference clk
>> +  "clk_usb3otg0_suspend"Controller suspend clk, can use 24 MHz or 32 KHz
>> +  "aclk_usb3"		Master/Core clock, have to be >= 62.5 MHz for SS
> operation
>
> clock names should always be in the scope of the device block (named after
> what it supplies). And looking at the dwc3-xilinx.txt binding, I'd suggest
> getting inspiration from their clock names (bus_clk, ref_clk, suspend_clk or
> so)
I'll fix the clock names next patch v5.
>
>> +Optional clocks:
>> +  "aclk_usb3otg0"	Aclk for specific usb controller clock.
>> +  "aclk_usb3_rksoc_axi_perf"  USB AXI perf clock.  Not present on all
>> platforms.
> The clock names looks pretty strange. What are they for? Especially as
> nothing seems to use them right now.

"aclk_usb3_rksoc_axi_perf", it's the clk for usb3 performance monitor module,
you can refer to the GRF_USB3_PERF_xxx. And we don't use the usb3 performance
monitor control registers right now.

>
>
>> +  "aclk_usb3_grf"	USB grf clock.  Not present on all platforms.
> for my own education, which part of the GRF does this clock supply?

"aclk_usb3_grf", it's the clk for USB3 grf, e.g. GRF_USB3OTGX_CONX

>
>
>> +
>> +Required child node:
>> +A child node must exist to represent the core DWC3 IP block. The name of
>> +the node is not important. The content of the node is defined in dwc3.txt.
>> +
>> +Phy documentation is provided in the following places:
>> +Documentation/devicetree/bindings/phy/rockchip,dwc3-usb-phy.txt
>> +
>> +Example device nodes:
>> +
>> +	usbdrd3_0: usb@...00000 {
>> +		compatible = "rockchip,dwc3";
>> +		clocks = <&cru SCLK_USB3OTG0_REF>, <&cru SCLK_USB3OTG0_SUSPEND>,
>> +			 <&cru ACLK_USB3>, <&cru ACLK_USB3OTG0>,
>> +			 <&cru ACLK_USB3_RKSOC_AXI_PERF>, <&cru ACLK_USB3_GRF>;
>> +		clock-names = "clk_usb3otg0_ref", "clk_usb3otg0_suspend",
>> +			      "aclk_usb3", "aclk_usb3otg0",
>> +			      "aclk_usb3_rksoc_axi_perf", "aclk_usb3_grf";
>> +		#address-cells = <2>;
>> +		#size-cells = <2>;
>> +		ranges;
>> +		status = "disabled";
>> +		usbdrd_dwc3_0: dwc3@...00000 {
>> +			compatible = "snps,dwc3";
>> +			reg = <0x0 0xfe800000 0x0 0x100000>;
>> +			interrupts = <GIC_SPI 105 IRQ_TYPE_LEVEL_HIGH>;
>> +			dr_mode = "otg";
>> +			status = "disabled";
>> +		};
>> +	};
>
>