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

[H. Nikolaus Schaller]

> 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?

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