RE: [PATCH v2 5/5] usb:cdns3 Add Cadence USB3 DRD Driver

[Pawel Laszczak]

Hi, 

>On Thu, Jan 10, 2019 at 09:30:41AM +0800, Peter Chen wrote:
>> On Mon, Dec 24, 2018 at 12:44 AM Pawel Laszczak <pawell@xxxxxxxxxxx> wrote:
>> - debugfs is nice to have feature, I suggest removing it at this
>> initial version. Besides, role switch
>> through /sys is normal feature, the end user may use it at real
>> product, so, it is better at device's
>> /sys entry instead of debugfs.
>>
>> - I don't know why you add "disable" at debugfs, please comment.
>
>As you imply here, no real-world functionality should ever be in
>debugfs as it is an optional system component and kernel code should
>work just fine without it being enabled (as more and more systems are
>disabling it due to the obvious security problems it has.)
>
"disable" it's not required. It's used for testing. It allows to enable/disable the current role.
It can be used for testing eg. connect/disconnect event. 

I mainly test the driver remotely and I can't do connect/disconnect by USB cable. 
"disable" allow me to get trace log from host/device without disconnecting cable:
I'm using the fallowing sequence:
 - load cdns3.ko modules 
 - echo 1 > disable - disable current role
 - echo cdns3:* tracing/set_event 
 - echo 0 > disable  - enable role again 
 - cat tracing/trace. 

Pawel