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

[H. Nikolaus Schaller]

> Am 19.02.2019 um 20:33 schrieb Andreas Kemnade <andreas at kemnade.info>:
> 
> On Mon, 18 Feb 2019 09:07:27 +0100
> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
> 
>> 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.  
>> 
>> I have checked and it did no longer apply. So yes, it was probably forgotten
>> to convert into a correct fix.
>> 
>> This one appears to apply:
>> 
>> commit 1a27badcf1ce03cb8bc69bdb72d76fd27660cf49 (HEAD -> letux/musb-fixes)
>> Author: Andreas Kemnade <andreas at kemnade.info>
>> Date:   Mon Feb 13 17:16:57 2017 +0100
>> 
>>    musb: disable b_host wait timeout for y-cable usage
>> 
>>    To be able to use Y-cables to power the device and use it as host at
>>    the same time, disable the b_waitacon timeout.
>> 
>>    Signed-off-by: Andreas Kemnade <andreas at kemnade.info>
>> 
>> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
>> index b7d56272f9d1..780787540b85 100644
>> --- a/drivers/usb/musb/musb_core.c
>> +++ b/drivers/usb/musb/musb_core.c
>> @@ -718,9 +718,15 @@ static void musb_handle_intr_suspend(struct musb *musb, u8 devctl)
>>                if (musb->is_active) {
>>                        musb->xceiv->otg->state = OTG_STATE_B_WAIT_ACON;
>>                        musb_dbg(musb, "HNP: Setting timer for b_ase0_brst");
>> +               /* If trying to switch to b_host without a real
>> +                * hnp reset (y-cables and such) the timer might
>> +                * be disturbing
>> +                */
>> +#if 0
>>                        mod_timer(&musb->otg_timer, jiffies
>>                                + msecs_to_jiffies(
>>                                                OTG_TIME_B_ASE0_BRST));
>> +#endif
>>                }
>>                break;
>>        case OTG_STATE_A_WAIT_BCON:
>> 
>> 
>>> - 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.
>>> 
> 
> ok, played a bit around with it. Reverting it enables me to do
> all the things I do with that otg usb.

I have included the above patch in 5.0-rc7 and scheduled for
the next 4.19/4.20 (forgot to include it immediately).

Regarding USB/OTG I want to do some tests myself. Then we should
raise fingers and submit the revert...

BR,
Nikolaus