linux-kernel - Re: [PATCH] usb: musb: dsps: handle the otg_state_a_wait_vrise

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Date:	Tue, 8 Dec 2015 09:16:59 -0600
From:	Felipe Balbi <balbi@...com>
To:	Bin Liu <b-liu@...com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: dsps: handle the otg_state_a_wait_vrise_timeout case


Hi,

Bin Liu <b-liu@...com> writes:
>>>>> "This bit should be set high prior to setting bit 0 and cleared after bit 0
>>>>> is cleared."
>>>>>
>>>>> and on the other side:
>>>>> "Both the soft_reset and soft_reset_isolation bits should be asserted
>>>>> simultaneously."
>>>>>
>>>>> The hang you saw could be explained by the following:
>>>>> "Setting only the soft_reset_isolation bit will cause all USB0 output
>>>>> signals to go to a known constant value via multiplexers.
>>>>> This will
>>>>> prevent future access to USB0."  page 2567
>>>>
>>>> good catch. Setting them together makes the hang go away.
>>>>
>>>> I still have the other problem, which is legacy IRQ reporting mode not
>>>> really working.
>>>>
>>>
>>> I never tried to change the IRQ mapping. The 8 MUSB interrupt will be
>>> the same no matter where they are reported from. What do you expect when
>>> switch to the MUSB IRQ reporting mode?
>>
>> read events from MUSB's registers instead of TI's :-) so, MUSB_INTRUSB,
>> MUSB_INTRRX and MUSB_INTRTX.
>>
> I meant you expect to see any different event when switch to MUSB IRQ 
> mode? The TI wrapper just reports the same 8 interrupt events. I don't 
> think you would get any difference.

still valid to make sure ;-)

> BTY, I think I miss some context here. This Gregory's patch is trying to 
> fix the OTG state machine problem in musb_dsps, which is replicated with 
> a cable without a device connected. But it also mentions about 
> non-compliant MSC devices. How are the thumb drives related to this OTG 
> state issue?

the problem seems to be caused by the missing disconnect IRQ. Not really
missing, but taking seconds to trigger.

-- 
balbi

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