MUSB dual-role on AM335x behaving weirdly

[Bin Liu]

Felipe,

On Thu, May 14, 2015 at 2:29 PM, Felipe Balbi <balbi at ti.com> wrote:
> On Thu, May 14, 2015 at 02:29:20PM -0500, Bin Liu wrote:
>> On Thu, May 14, 2015 at 2:21 PM, Felipe Balbi <balbi at ti.com> wrote:
>> > On Thu, May 14, 2015 at 02:19:28PM -0500, Bin Liu wrote:
>> >> Felipe,
>> >>
>> >> On Thu, May 14, 2015 at 2:04 PM, Felipe Balbi <balbi at ti.com> wrote:
>> >> > On Thu, May 14, 2015 at 12:49:07PM -0500, Felipe Balbi wrote:
>> >> >> On Thu, May 14, 2015 at 12:40:31PM -0500, Felipe Balbi wrote:
>> >> >> > On Thu, May 14, 2015 at 12:07:00PM -0500, Felipe Balbi wrote:
>> >> >> > > Hi,
>> >> >> > >
>> >> >> > > On Wed, Feb 25, 2015 at 01:11:22PM +0100, Yegor Yefremov wrote:
>> >> >> > > > On 25.02.2015 12:11, Maxime Ripard wrote:
>> >> >> > > > > On Tue, Feb 24, 2015 at 11:33:57AM -0600, Felipe Balbi wrote:
>> >> >> > > > >> Hi,
>> >> >> > > > >>
>> >> >> > > > >> On Tue, Feb 24, 2015 at 05:50:50PM +0100, Maxime Ripard wrote:
>> >> >> > > > >>> Hi Felipe,
>> >> >> > > > >>>
>> >> >> > > > >>> On Tue, Feb 24, 2015 at 08:54:01AM -0600, Felipe Balbi wrote:
>> >> >> > > > >>>> Hi,
>> >> >> > > > >>>>
>> >> >> > > > >>>> On Tue, Feb 24, 2015 at 11:39:11AM +0100, Maxime Ripard wrote:
>> >> >> > > > >>>>> 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
>> >> >> > > > >>
>> >> >> > > > >> since 3.16 ?
>> >> >> > > > >
>> >> >> > > > > That's what Yegor said. I never saw it working with 3.15 either.
>> >> >> > > >
>> >> >> > > > I've used 3.15.1 and 3.15.2 with this set of patches:
>> >> >> > > > https://github.com/visionsystemsgmbh/onrisc_br_bsp/tree/master/board/vscom/kernel-patches/linux-3.15
>> >> >> > > >
>> >> >> > > > And it worked so far. The system:
>> >> >> > > > http://www.visionsystems.de/produkte/baltos-ir-5221.html
>> >> >> > >
>> >> >> > > I've had more time to look into this (thanks Yegor for sponsoring a
>> >> >> > > test/dev platform) what I noticed is that Connect IRQ takes seconds to
>> >> >> > > fire up.  Below a tiny log snippet after pluging USB OTG adapter cable
>> >> >> > > that came with IR5521:
>> >> >> > >
>> >> >> > > | [ 1227.200514] musb-hdrc musb-hdrc.1.auto: usbintr (100) epintr(0)
>> >> >> > >
>> >> >> > > Cable connected. ID is grounded. 0x100 == DRVVBUS IRQ
>> >> >> > >
>> >> >> > > | [ 1227.206788] musb-hdrc musb-hdrc.1.auto: VBUS on (a_wait_vrise), devctl 19
>> >> >> > >
>> >> >> > > MUSB starts to wait for VBUS to reach Session valid threshold
>> >> >> > >
>> >> >> > > | [ 1230.281159] musb-hdrc musb-hdrc.1.auto: usbintr (10) epintr(0)
>> >> >> > >
>> >> >> > > 3 seconds later connect interrupt happens. Looking at VBUS charge time
>> >> >> > > with a scope, it's quite ok. VBUS charges in about 1.77ms. I'll dig
>> >> >> > > further into this.
>> >> >> >
>> >> >> > even more weird. If I disconnect device from OTG adapter, rather than
>> >> >> > OTG adapter from IR5521, this leave ID pin grounded, which means DRVVBUS
>> >> >> > is still asserted and VBUS remains above session valid threshold.
>> >> >> >
>> >> >> > Even in this case, when I connect the device on the other end of the
>> >> >> > cable, I still see some 3 seconds delay from the time device is
>> >> >> > connected, to the time connect IRQ fires up.
>> >> >>
>> >> >> seems to be a problem with the USB stick I'm using. Tested two other
>> >> >> devices and they connect right away.
>> >> >
>> >> > ok, fixing DRD on AM335x will take longer than I originally expected,
>> >> > probably won't be ready for v4.2 :-(
>> >>
>> >> Are you able replicate the issue with TI AM335x GP EVM? I am wondering
>> >> if the is custom board design problem? have you checked the custom
>> >> board schematics?
>> >
>> > don't have either AM335x GP EVM nor schematics for this board. But it's
>> > certainly not a problem with the board. It's very easy to replicate the
>> > problem:
>> >
>> > Set dr-mode to otg, load g_zero, connect to PC and as quickly as you
>> > can, remove cable and attach otg cable with a mouse or whatever on the
>> > other end.
>> >
>> > First time, mouse won't enumerate (no IRQs fire) remove and connect
>> > again. You should see a Babble IRQ.
>>
>> And this only happens with 3.16+, not older kernels? I have a GP EVM,
>> and can try to take a look.
>
> yeah, if you can try with v4.1-rc3, that'd be great. I also see that
> disconnect IRQ takes a while to fire, but VBUS drops rather fast on this
> board (< 10ms to discharge VBUS).

How low is VBUS after 10ms? I don't have a scope with me right now,
but I see Diconnect IRQ happened right away if I short VBUS to ground
right after disconnected from the host. So I suspect is that VBUS
discharge takes ~20sec on my board, which is the time taken for MUSB
from b_peripheral to b_idle.

BTY, it seems Disconnect IRQ is expected for MUSB in device mode. I
never pay attention on this.

Regards,
-Bin.

>
>> /me just figured out the modem issue, and in a very good mood now ;)
>
> hey, congrats :-)
>
> --
> balbi