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Date:   Tue, 26 Sep 2023 10:14:15 +0300
From:   Tony Lindgren <tony@atomide.com>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     kernel list <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-omap@vger.kernel.org, sre@kernel.org, nekit1000@gmail.com,
        mpartap@gmx.net, merlijn@wizzup.org, martin_rysavy@centrum.cz,
        phone-devel@vger.kernel.org, maemo-leste@lists.dyne.org
Subject: Re: droid4 -- weird behaviour when attempting to use usb host
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* Pavel Machek <pavel@ucw.cz> [230925 14:36]:
> Hi!
> 
> I'm having some fun with usb host. Good news is it works with
> externally powered hub... after a while. I get some error messages
> about inability to go host mode, but with enough patience it
> eventually does enter host mode and I see my keyboard/mouse.
> 
> And usually in that process, one of my cpu cores disappear. top no
> longer shows 2 cores, and I was wondering for a while if d4 is
> single-core system. It is not, my two cores are back after reboot.
> 
> That's with 6.1.9 kernel from leste. Ideas how to debug this would be
> welcome. (Do you use usb host?)

You are using a "proper" non-standard usb micro-b cable that grounds
the id pin, right?

If not, try with one of those as it allows the hardware to do what it's
supposed to do.

And presumably you don't have a hacked usb hub that feeds back the
vbus to your phone, right?

If you have, that should not be used as the pmic can feed vbus.

Regards,

Tony