Re: [PATCH] usb: phy: Move R-Car Gen2 driver registration to postcore_inictall

[Valentine <valentine.barshak@cogentembedded.com>]

On 10/30/2013 06:12 PM, Greg KH wrote:
> On Wed, Oct 30, 2013 at 01:56:25PM +0400, Valentine wrote:
>> On 10/30/2013 03:57 AM, Greg KH wrote:
>>> On Tue, Oct 29, 2013 at 09:19:09PM +0400, Valentine wrote:
>>>> On 10/29/2013 09:00 PM, Laurent Pinchart wrote:
>>>>> Hi Valentine,
>>>>>
>>>>> Thank you for the patch.
>>>>>
>>>>> On Tuesday 29 October 2013 20:21:06 Valentine Barshak wrote:
>>>>>> USB phy controls USB channels 0 and 2 which are shared between
>>>>>> PCI USB host controllers and USBHS/USBSS respectively.
>>>>>>
>>>>>> This Initializes USB phy driver earlier because we need it
>>>>>> before PCI USB host controllers are initialized.
>>>>>
>>>>> Can't you use deferred probing ?
>>>>
>>>> No, unfortunately this doesn't work with PCI.
>>>> We need the USB PHY set up before the PCI driver starts.
>>>> PCI controllers should be initialized via subsys_initcall and can't be built as a module.
>>>> Deferred probing is done at late_initcall and that's far too late in this case.
>>>>
>>>> The MXS USB phy uses the similar approach, initializing the driver via postcore_initcall.
>>>
>>> I _HATE_ this "make this driver later than the others" mess.  I'll not
>>
>> This is actually "make this driver before the others" mess.
>>
>>> take patches that move drivers to different initcalls, sorry.  Please
>>> fix up the link order, or use deferred probing, as that is why it was
>>> created.
>>>
>>
>> This is needed for the PCI EHCI/OHCI drivers to operate correctly on R-Car Gen platform
>> since it has built-in PCI host controllers that share USB I/O with USBHS/USBSS devices.
>> The phy has to be configured before the PCI EHCI/OHCI devices are probed.
>>
>> I'd really appreciate if you could give me a hint on how to fix the PCI EHCI/OHCI driver
>> to use deferred probing, or fix the link order without creating a bigger mess.
>
> Just change the PCI driver to use deferred probing, it isn't that hard
> to do so.
>

Do you mean to change usb_hcd_pci_probe() to return -EPROBE_DEFER if the phy is not ready?
Or should I defer the whole PCI subsystem initialization (pci_common_int)?

> good luck,

Thanks,
Val.

>
> greg k-h
>