MUSB dual-role on AM335x behaving weirdly

[Maxime Ripard]

On Thu, Feb 05, 2015 at 02:21:42PM +0100, Maxime Ripard wrote:
> Hi,
> 
> On Thu, Jan 22, 2015 at 08:37:45AM +0100, Yegor Yefremov wrote:
> > I have the same experience with 3.15. The switching is working when
> > CONFIG_USB_MUSB_DUAL_ROLE is set and dr_mode = "otg". But since 3.16
> > it seems to be broken. Still had no time to bisect this.
> 
> I've been giving a few versions (from v3.15 to Tuesday's linux-next) a
> try, and I always see the same behaviour now:
> 
>   - Booting as a gadget (ie, with a USB cable plugged in), and
>     swapping the cable for a (real, this time) USB OTG cable with a
>     USB key never works. When the device is plugged, all I get is
> 
> [  262.944846] usb 1-1: new high-speed USB device number 2 using musb-hdrc
> [  278.064748] usb 1-1: device descriptor read/64, error -110
> 
>     Putting in back in gadget results with a load of continuous:
> [  315.258839] musb_bus_suspend 2484: trying to suspend as a_wait_vfall while active
> 
>   - Booting as a host, or with nothing connected to it actually work,
>     up to a few plug-a-device-then-plug-a-host cycles, where you end
>     up with the following logs when disconnecting the device (somehow,
>     it always happens when it is set in host mode).
> 
> [   12.969075] CAUTION: musb: Babble Interrupt Occurred
> [   12.974445] CAUTION: musb: Babble Interrupt Occurred
> [   12.979637] musb_stage0_irq 789: unhandled DISCONNECT transition (a_wait_bcon)
> [   12.988498] usb 1-1: USB disconnect, device number 2
> [   13.071849] musb-hdrc musb-hdrc.0.auto: Restarting MUSB to recover from Babble
> 
>     Plugging back our USB cable, with the AM335x acting as a device
>     work once. Then, when it switches to the host mode, we end up with
>     the same scenario than in the coldplug as gadget case: USB read
>     error, before then having all the a_wait_vfall messages.

Guys, any ideas/hints?

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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