Re: [PATCH v2 2/3] usb: chipidea: imx: support disabling runtime-pm

Philippe Schenker
2020-07-20T07:51:36Z

On Mon, 2020-07-20 at 03:44 +0000, Peter Chen wrote:
>
> > On Wed, 2020-07-15 at 00:51 +0000, Peter Chen wrote:
> > > > The Toradex Colibri iMX6ULL board has a special USB hardware
> > > > design.
> > > > With runtime-pm enabled USB reset itself continuously.
> > > > Furthermore
> > > > the OTG port is also not enumerating devices if the Chipidea IP
> > > > is
> > > > in runtime sleep mode and a device or host gets plugged in.
> > > >
> > >
> > > Hi Philippe,
> > >
> > > You may describe the detail what's the special USB hardware design
> > > for
> > > your board,
> >
> > If I only knew the root-cause of that problem - unfortunately I
> > don't.
> > That's also why I have such a hard time to describe it.
> >
> > > and why it causes the problem, and why disable runtime pm could
> > > fix
> > > this issue, then,
> >
> > I cannot provide the 'why' part yet. I'll try something more and
> > hope I can provide
> > you guys with the exact description.
> >
> > > the other users could know if it could apply to their platforms or
> > > not
> > > in future.
> >
> > I only found out about it because you were pointing me in that
> > direction. I debugged
> > for hours now and didn't came to the root-cause of the issue. I
> > think to really
> > understand it I would need to know much more about the Chipidea IP.
> >
> > I'll get back to you guys with a proposal for a new description.
> >
>
> Philippe, is it possible to share your USB hardware design at 6ULL?

It's actually pretty simple: We have on USB_OTG1_VBUS a 1uF capacitor
and +3.0V on VDD_USB_CAP together with 100n and 10u bypass caps. Now the
big problem is that the driver can not detect the 5V on VBUS signal.

I tried to 'inject' 5V to that pin last week and things got really
better with runtime-pm. But I still thinks disabling it for our board
would make sense.

I'll send a new description today where I try to point to VBUS signal
not connected.

Philippe

> And how ci_hdrc_gadget_connect is called when the runtime pm is
> disabled?
>
> Thanks,
> Peter
>