Re: [PATCH v2 4/4] usb: dwc3: Workaround for super-speed host on dra7 in dual-role mode

[Chanwoo Choi]

Hi,

2017-02-24 21:02 GMT+09:00 Roger Quadros <rogerq@xxxxxx>:
> +Chanwoo
>
> Hi Vivek,
>
> On 23/02/17 10:34, Vivek Gautam wrote:
>>
>>
>> On 02/16/2017 06:36 PM, Roger Quadros wrote:
>>> dra7 OTG core limits the host controller to USB2.0 (high-speed) mode
>>> when we're operating in dual-role.
>>>
>>> We work around that by bypassing the OTG core and reading the
>>> extcon framework directly for ID/VBUS events.
>>>
>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>>> ---
>>>   Documentation/devicetree/bindings/usb/dwc3.txt |   2 +
>>>   drivers/usb/dwc3/core.c                        | 169 ++++++++++++++++++++++++-
>>>   drivers/usb/dwc3/core.h                        |   5 +
>>>   3 files changed, 170 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
>>> index e3e6983..9955c0d 100644
>>> --- a/Documentation/devicetree/bindings/usb/dwc3.txt
>>> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt
>>> @@ -53,6 +53,8 @@ Optional properties:
>>>    - snps,quirk-frame-length-adjustment: Value for GFLADJ_30MHZ field of GFLADJ
>>>       register for post-silicon frame length adjustment when the
>>>       fladj_30mhz_sdbnd signal is invalid or incorrect.
>>> + - extcon: phandle to the USB connector extcon device. If present, extcon
>>> +    device will be used to get USB cable events instead of OTG controller.
>>>      - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
>>>   diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index 619fa7c..b02d911 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>
>> [snip]
>>
>>> @@ -1587,6 +1727,14 @@ static int dwc3_probe(struct platform_device *pdev)
>>>         dwc3_get_properties(dwc);
>>>   +    if (dev->of_node) {
>>> +        if (of_property_read_bool(dev->of_node, "extcon"))
>>> +            dwc->edev = extcon_get_edev_by_phandle(dev, 0);
>>
>> Don't we want separate edev's for vbus and id ?
>> One can have separate pins connected to them and in that case
>> we can't get the events out of one pin only.
>
> Is such kind of hardware really there? Ideally one extcon device
> represents one connector. So VBUS and ID events of a single USB
> port should come on one extcon device.
> If it doesn't then you need to fix your platforms extcon driver
> so that it does.
> Chanwoo can correct me if I'm wrong on this understanding.
>
> Currently, if VBUS and ID come on GPIOs the extcon-usb-gpio driver
> takes care of both.

Basically, one extcon device driver can support the multiple
external connectors if the detection h/w or port is same.

One extcon device with extcon-usb-gpio.c can support the detection
of both ID and VBUS.

But, if there is any issue of h/w schematic, we need to consider
how to use the extcon device.

>
>>
>>> +
>>> +        if (IS_ERR(dwc->edev))
>>> +            return PTR_ERR(dwc->edev);
>>
>>  Took me a while to get to this. :)
>>
>>                 if (IS_ERR(dwc->edev)) {
>>                        ret = PTR_ERR(dwc->edev);
>>                        goto err0;
>>                 }
>>
>> We want to reset the res->start back to its original offset.
>>
>> Testing this series currently. Will get back with my results.
>>
>>
> Thanks :)
>
> --
> cheers,
> -roger

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics