Re: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

From: Felipe Balbi
Date: Tue Aug 13 2019 - 01:15:42 EST



Hi,

Roger Quadros <rogerq@xxxxxx> writes:
>> Roger Quadros <rogerq@xxxxxx> writes:
>>>> The sysfs file we expose from the class for the role switches is
>>>> primarily meant for supporting proprietary protocols that require us
>>>> to basically override the connector USB data role. The default role
>>>> should always be selected in the drivers.
>>>
>>> OK. Let's take this example
>>> - Port is dual-role port micro AB.
>>> - microAB to type-A adapter is connected which pulls ID low. port transitions
>>> to "host" role by the controller driver.
>>> - proprietary protocol want to switch role to device role so writes "device" to
>>> mode switch sysfs. port transitions to "device" role.
>>>
>>> Now, how does controller driver know to fall back to HW based role switching?
>>
>> Use a 'disconnect' or 'suspend' event to go reset it? But that should,
>> probably, be done at kernel space, no?
>>
>
> Yes that could be one option.
> So after a disconnect, sysfs role should reflect actual hardware role. correct?

that would be my expectation

--
balbi