Chrome Version: 68.0.3440.118
Chrome OS Version: Google_Eve.9584.151.0 release 10718.88.2
Chrome OS Platform: Google Pixelbook
Network info: n/a

* Please specify Cr-* of the system to which this bug/feature applies (add
the label below).
?

* Summary:

Pixelbook is now used in the interoperability part of USB certification testing by USB IF approved labs.

But it appears to have an issue that affects USB certification.

Specifically, Pixelbook does not enable Rpd=15KOhm pull-down resistor on USB D+ line until portable device enables the D+ pull-up.

This interferes with charger detection (USB Battery Charger specification 1.2) and can result in detecting Pixelbook as a non-USB compliant wall-charger.

Please, refer to USB 2.0 specification, 7.1.5.1 "Low-/Full-speed Device Speed Identification".

* Expected Result:
Rpd attached to USB D+/D- with USB VBUS going high.

* Actual Result:
Rpd is not attached to at least USB D+ until portable device attaches Rpu.

* How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
Always.

* What is the impact to the user, and is there a workaround? If so, what is
it?
This is a non-USB compliant behaviour and can affect certification of USB devices.

* Please provide any additional information below. Attach a screen shot or
log if possible.

This can be seen on the attached scope traces, one for normal port on a PC that has Rpd on D+/D-, another for Pixelbook that does not appear to have Rpd on D+.

* For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.

n/a


 

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