Re: [PATCH v3 4/4] doc: usb: ci-hdrc-usb2: Add pinctrl properties for HSIC pin groups

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Hi Peter, hi Fabio,

On 30.11.18 03:33, PETER CHEN wrote:
>   
>>
>> On Tue, Nov 27, 2018 at 7:31 AM PETER CHEN <peter.chen@xxxxxxx> wrote:
>>>
>>> For USB HSIC, the data and strobe pin needs to be pulled down at
>>> default, we consider it as "idle" state. When the USB host is ready to
>>> be used, the strobe pin needs to be pulled up, we consider it as
>>> "active" state.
>>>
>>> Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
>>> ---
>>>   Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt | 8 +++++++-
>>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
>>> b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
>>> index 529e51879fb2..1e5e7ddfb1a5 100644
>>> --- a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
>>> +++ b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
>>> @@ -80,7 +80,10 @@ Optional properties:
>>>     controller. It's expected that a mux state of 0 indicates device mode and a
>>>     mux state of 1 indicates host mode.
>>>   - mux-control-names: Shall be "usb_switch" if mux-controls is specified.
>>> -- pinctrl-names: Names for optional pin modes in "default", "host", "device"
>>> +- pinctrl-names: Names for optional pin modes in "default", "host", "device".
>>> +  In case of HSIC-mode, "idle" and "active" pin modes are mandatory.
>>> +In this
>>> +  case, the "idle" state needs to pull down the data and strobe pin
>>> +  and the "active" state needs to pull up the strobe pin.
>>>   - pinctrl-n: alternate pin modes
>>>
>>>   i.mx specific properties
>>> @@ -110,4 +113,7 @@ Example:
>>>                  phy-clkgate-delay-us = <400>;
>>>                  mux-controls = <&usb_switch>;
>>>                  mux-control-names = "usb_switch";
>>> +               pinctrl-names = "idle", "active";
>>> +               pinctrl-0 = <&pinctrl_usbh2_1>;
>>> +               pinctrl-1 = <&pinctrl_usbh2_2>;
>>
>> I would put the "idle" and "active" entries inside a explicit section for HSIC.
>>
>> Otherwise, it may confuse people using non-HSIC bindings.
> 
> It is just an example; the user should check the meaning for optional properties before
> using it, like the property "phy-clkgate-delay-us", only imx7d/7s needs it.

There are many other optional properties for this driver and a lot of 
them are not in the given example. Maybe we should just keep the 
pinctrls for HSIC-mode out of the example, too?

Regards,
Frieder




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