Re: [PATCH 0/4] musb fixes for v4.9-rc cycle

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Bin Liu <b-liu-l0cyMroinI0@public.gmane.org> [161111 08:25]:
> On Fri, Nov 11, 2016 at 01:39:28AM +0200, Laurent Pinchart wrote:
> > Hello,
> > 
> > On Friday 11 Nov 2016 00:27:52 Laurent Pinchart wrote:
> > > On Thursday 10 Nov 2016 13:42:34 Tony Lindgren wrote:
> > > > * Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org> [161110 13:29]:
> > > >> I had to disable CONFIG_USB_GADGET is compiling it as a module prevents
> > > >> selecting CONFIG_NOP_USB_XCEIV=y, which is a dependency for
> > > >> CONFIG_USB_EHCI_HCD_OMAP=m.
> > > >> 
> > > >> The new configuration resulted in a few changes, among which the most
> > > >> notable is
> > > >> 
> > > >> -# CONFIG_USB_MUSB_HOST is not set
> > > >> -# CONFIG_USB_MUSB_GADGET is not set
> > > >> -CONFIG_USB_MUSB_DUAL_ROLE=y
> > > >> +CONFIG_USB_MUSB_HOST=y
> > > >> 
> > > >> I then get the same error as originally reported.
> > > > 
> > > > Yeah OK, that's the problem.. We still have musb hardware
> > > > trying to do things on it's own and phy trying to detect
> > > > the state.
> > > > 
> > > > Any ideas why we have a dependency like that in Kconfig?
> > > 
> > > Well, with CONFIG_USB_GADGET disabled, I don't expect CONFIG_USB_MUSB_GADGET
> > > to be enabled. MUSB can only operate in host mode in that case, so musb->
> > > xceiv->otg->state = OTG_STATE_A_IDLE makes sense.
> > 
> > I've tried to investigate this but I'm not familiar enough with the MUSB 
> > driver to reach any conclusion. Felipe, if you have time could you give me a 
> > hand ?
> > 
> > To summarize the issue, on a pandaboard-es where the MUSB is wired to an OTG 
> > connector with mode rightfully set to MUSB_PORT_MODE_DUAL_ROLE in DT, a kernel 
> > configured with CONFIG_USB_MUSB_HOST=y (for instance because CONFIG_USB_GADGET 
> > is disabled) will print an endless stream of the following meessage.
> > 
> > [    2.766174] musb_bus_suspend 2586: trying to suspend as a_idle while active
> 
> I don't have a omap3/4 platform to test on this, but I don't see this
> problem on am335x board.
> 
> > 
> > musb_init_controller() performs the following actions
> > 
> >         case MUSB_PORT_MODE_DUAL_ROLE:
> >                 status = musb_host_setup(musb, plat->power);
> >                 if (status < 0)
> >                         goto fail3;
> >                 status = musb_gadget_setup(musb);
> >                 if (status) {
> >                         musb_host_cleanup(musb);
> >                         goto fail3;
> >                 }
> >                 status = musb_platform_set_mode(musb, MUSB_OTG);
> >                 break;
> > 
> > and as gadget support is disabled musb_gadget_setup() compiles to a no-op 
> > inline function. The system is thus configured in host mode by 
> > musb_host_setup() with musb->xceiv->otg->state = OTG_STATE_A_IDLE. A later 
> > call to musb_start() verifies the condition
> > 
> >         if (musb->port_mode != MUSB_PORT_MODE_HOST &&
> >                         musb->xceiv->otg->state != OTG_STATE_A_WAIT_BCON &&
> >                         (devctl & MUSB_DEVCTL_VBUS) == MUSB_DEVCTL_VBUS) {
> 
> To get there, devctl[MUSB_DEVCTL_VBUS] bits have to be set, where does the
> vbus voltage come from? Session is not on yet.
> 
> > 
> > and sets musb->is_active to 1. Later, musb_bus_suspend() complains because 
> > is_active is not 0.
> > 
> > What is wrong in that sequence ?

I think the issue is pandaboard connected to a PC with mini-B
cable while musb is being forced to host mode?

Regards,

Tony
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