On Mon, 2020-07-20 at 08:06 +0000, Peter Chen wrote:

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On Mon, 2020-07-20 at 03:44 +0000, Peter Chen wrote:

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On Wed, 2020-07-15 at 00:51 +0000, Peter Chen wrote:

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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.

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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.

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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.

Could you confirm it does not see VBUS at register OTGSC? If it is,
how can it work with runtime
disabled, the USBCMD.RS setting (ci_hdrc_gadget_connect is called)
depends on VBUS.

Peter

For this reason I'm using a workaround in extcon like this:

extcon = <&extcon_usbc_det>, <&extcon_usbc_det>;

I know that this is undocumented and wrong, but it works for our
hardware. With this and enabled runtime-pm devices do not get
enumerated.

But with runtime-pm disabled, devices get enumerated.

Further with this workaround the VBUS signal gets 'simulated'
in hw_read_otgsc.

Another problem with runtime-pm enabled is that with no devices plugged
into USB it resets itself every ~1 second.

Philippe.

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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

quoted

And how ci_hdrc_gadget_connect is called when the runtime pm is
disabled?

Thanks,
Peter

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