fix for lantiq (danube) usb

[John Crispin]

On 03.07.20 19:23, Luca Olivetti wrote:
> El 3/7/20 a les 18:42, John Crispin ha escrit:
>>
>> On 03.07.20 18:10, Luca Olivetti wrote:
>>> Hello,
>>>
>>> around 2 years ago, this patch
>>>
>>> https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=6eaf8b3d89571992a0aa7142cfab3f1dcef3c802#patch7 
>>>
>>>
>>> broke the usb on my arv7518pw: when it tries to power up the usb it 
>>> returns error -537 (EPROBE_DEFER, see 
>>> https://bugs.openwrt.org/index.php?do=details&task_id=1634).
>>>
>>> [ 5.431505] dwc2 1e101000.usb: 1e101000.usb supply vusb_d not found, 
>>> using dummy regulator
>>> [ 5.438418] dwc2 1e101000.usb: 1e101000.usb supply vusb_a not found, 
>>> using dummy regulator
>>> [ 5.446581] dwc2 1e101000.usb: dwc2_core_reset() HANG! Soft Reset 
>>> GRSTCTL=80000001
>>> [ 5.593255] dwc2 1e101000.usb: DWC OTG Controller
>>> [ 5.596565] dwc2 1e101000.usb: new USB bus registered, assigned bus 
>>> number 1
>>> [ 5.603417] dwc2 1e101000.usb: irq 62, io mem 0x1e101000
>>> [ 5.608632] dwc2 1e101000.usb: startup error -517
>>> [ 5.613124] dwc2 1e101000.usb: USB bus 1 deregistered
>>> [ 5.618080] dwc2 1e101000.usb: dwc2_hcd_init() FAILED, returning -517
>>>
>>>
>>> If I revert the above patch, the usb initializes correctly, but 
>>> there's no 5V on the port so it doesn't work.
>>>
>>> I hacked a fake led on gpio 14 so I can turn on the 5V from user 
>>> space, and the usb works (I tried with a memory stick and an rt73 
>>> wifi stick, an rtl8812au doesn't work but I think because its driver 
>>> is ... meh).
>>>
>>> What's the proper way to turn on the 5V on gpio 14 (i.e. fix the 
>>> -EPROBE_DEFER error)?
>>>
>>>
>>> I suppose that the issue also affects other danube based devices, 
>>> but I can only test the one I have.
>>>
>>> This is against 19.07.3
>>
>>
>> Why not use the gpio regulator ?
>
> Because I don't know how :-(
>
https://www.kernel.org/doc/Documentation/devicetree/bindings/regulator/fixed-regulator.yaml