[Letux-kernel] musb otg/y-cable regressions, OTG support removal

[H. Nikolaus Schaller]

> Am 18.02.2019 um 08:55 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> 
>> Am 18.02.2019 um 08:53 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> 
>> Hi,
>> 
>>> Am 18.02.2019 um 07:58 schrieb Andreas Kemnade <andreas at kemnade.info>:
>>> 
>>> Hi,
>>> 
>>> after quite some searching why b_host mode only works very randomly, I found
>>> out that
>>> - musb: disable b_host wait timeout for y-cable usage
>>> is missing in >= letux-4.18. Seems to be forgotten in a conflict resolution.
>> 
>> Ok. Do you have a reference to the original patch?
>> 
>>> - and them we have this one
>>> commit 0a9134bd733bbb99bd18f5520a488960170271f2
>>> Author: Bin Liu <b-liu at ti.com>
>>> Date:   Mon May 21 08:42:19 2018 -0500
>>> 
>>>  usb: musb: disable otg protocol support
>>> 
>>>  As decided in the discussion [1] we are deleting the otg protocol
>>>  support from the musb drivers.
>>> 
>>>  First this patch disables the flags for enabling the otg protocols. We
>>>  will later gradually delete the otg protocol code from the musb drivers.
>>> 
>>>  [1] https://www.spinics.net/lists/linux-usb/msg167003.html
>>> 
>>>  Signed-off-by: Bin Liu <b-liu at ti.com>
>>>  Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
>>> 
>>> that seems also to influence things.
>> 
>> Hm. What are the effects of this? Does it influcence OTG operation on GTA04?
> 
> Especially there is something in the referenced discussion which says:
> 
> "such as adding otg fsm, musb runtime
> PM, and musb otg state moving from musb to musb->xceiv..."
> 
> So is there still OTG but just provided differently? What is musb->xceiv?

BTW: Greg called to be cautious:

https://www.spinics.net/lists/linux-usb/msg166958.html

So if we still need it we can raise our finger.

> 
>> 
>> Well, we never had a really OTG compatible socket, just the OTG mode.
>> 
>> BR,
>> Nikolaus
>> 
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