Re: unhandled interrupt from otg port

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 02/19/2013 03:17 PM, Marc Dietrich wrote:
> On Tuesday 19 February 2013 23:12:53 Marc Dietrich wrote:
>> Stephen,
>>
>> On Tuesday 19 February 2013 10:03:47 Stephen Warren wrote:
>>> On 02/17/2013 04:48 AM, Marc Dietrich wrote:
>>>> Hi,
>>>>
>>>> I sometimes see unhandled irq from the otg port on my AC100 (kernel 3.8.0-rc7).
>>>> This happens randomly when the a cable is pluged into the mini usb port. Seems
>>>> the port generates an interrupt on probe which isn't handled.
>>>
>>> Perhaps Venu can explain this; he is our USB expert.
>>>
>>>> Any ideas?
>>>
>>> I'm slightly confused by your description though; I assume this problem
>>> happens when you boot with a USB cable already plugged in, not when you
>>> first boot the system, then plug in a cable? Is the cable connected to a
>>> host PC, or to a device?
>>
>> the cable is connected to a host PC. It is not shown when connecting after the
>> system has booted. Unfortunately, I cannot generate the error reproducible, e.g.
>> I just tried 10 times and nothing was shown. Maybe just forget it for now if
>> no one has an obvious idea. I'll try to find some reproducable situation and will
>> report back.
> 
> arr, just found it: it happens when you load an uboot image via tegrarcm first - so this
> could be a kernel or uboot problem.

Ah, so that means that the Tegra boot ROM already initialized the USB
port in device mode to receive U-Boot. I assume you're not touching USB
in U-Boot at all, but loading the kernel/... from SD/eMMC. Then, the
kernel initializes/uses USB in host mode (since that's all we support so
far), and then you see the issue.

I reproduced this on Harmony. I'll file a bug and assign it to Venu.