Re: [RFC PATCH] drivers: usb: otg: add device tree support to otg library

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Hi,

On Tue, Jun 26, 2012 at 8:52 PM, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote:
> On 06/26/2012 04:15 PM, ABRAHAM, KISHON VIJAY wrote:
>>>>>> This is like bypassing the otg_library to add or get the phy :-(
>>>>>
>>>>> The problem is, we don't have _the_ phy, we have one phy per usb port
>>>>> and we have two USB ports.
>>>>
>>>> I think then this patch would solve your problem as it allows to add
>>>> multiple-phys of the same type?
>>>
>>> We have two USB ports, a OTG capable and a host-only one. Each one has a
>>> phy, which is used in the host mode and (if the USB port supports) in
>>> the peripheral mode.
>>>
>>> I didn't follow you multi phy patches closely, what's the exact meaning
>>> of type here. If this has already been discussed you can point me to the
>>> appropriate thread.
>>
>> What we were doing in multi-phy patch is, whenever a phy driver
>> registers itself in the otg library using usb_add_phy, it has to give
>> a phy type along with it (USB2 PHY, USB3 PHY,..). We weren't allowing
>> multiple phys of the same type, meaning in a system there cant be two
>> users who calls usb_add_phy(USB2PHY) because there wasn't any
>> reasonable way to get the phy.
>> The complete discussion thread is @
>> http://www.spinics.net/lists/linux-usb/msg63385.html
>
> Thanks, as Sascha pointed out, we have a strict phy<->usb relation, but
> there are two phys and two usbs in our system. However a generic phy
> layer would even be better.
>
>>>>>> Ideally you should make use of the otg library function for it. Having
>>>>>> a generic function in the otg library to get phy by phandle will help
>>>>>> other phy users to use it instead of implementing their own version of
>>>>>> get_phy from phandle.
>>>>>
>>>>> +1
>>>>>
>>>>> The code I pointed you at is the topmost patch in:
>>>>> https://github.com/riczhao/kernel-imx/commits/topics/usb-driver
>>>>> As soon as your code is available, let's convert it to use your generic
>>>>> function.
>>>>
>>>> Cool. Thanks :-)
>>>
>>> I pointed you to the code to make sure it fits our use case. To be
>>> precise, we have two of these usb to usbphy links in the dev-tree:
>>
>> yeah. So in the probe of your phy driver (fsl,imx28-usbphy), call
>> usb_add_phy. Then you can call devm_get_phy_by_phandle in the usb
>
> But we have two USB2 phys in the system, will 2 usb_add_phy() work?
Without this patch the phy types has to be different. If this patch
gets merged that restriction is removed. (You can add 2 phys without
any constraints).

Thanks
Kishon
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