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Can't connect to virtual USB serial port #10

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fhunleth opened this issue Jun 9, 2017 · 3 comments
Closed

Can't connect to virtual USB serial port #10

fhunleth opened this issue Jun 9, 2017 · 3 comments
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@fhunleth
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fhunleth commented Jun 9, 2017

When the Raspberry Pi Zero is connected to my Linux laptop, I see errors like this in dmesg:

[  463.159931] usb 2-1.7: new high-speed USB device number 5 using ehci-pci
[  468.231677] usb 2-1.7: device descriptor read/64, error -110
[  483.406923] usb 2-1.7: device descriptor read/64, error -110

On the Pi Zero, it looks like it's trying to enumerate the laptop:

[   22.412560] dwc2 20980000.usb: new device is high-speed
[   22.420708] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
[   22.588402] dwc2 20980000.usb: new device is high-speed
[   22.596563] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
[   27.660725] dwc2 20980000.usb: new device is high-speed
[   27.668904] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
[   42.836557] dwc2 20980000.usb: new device is high-speed
[   42.844617] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
[   43.012399] dwc2 20980000.usb: new device is high-speed
[   43.020361] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
[   53.492406] dwc2 20980000.usb: new device is high-speed
[   53.500478] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: failed queue (-11)
fhunleth added a commit that referenced this issue Jun 9, 2017
@fhunleth
Remove USB host mode support in kernel
bc16cfe 
This makes it so that the USB port *only* works in gadget mode. It fixes
an issue where the USB connection didn't work to my laptop. Presumably,
the USB stack thinks that the port should be run in host mode. However,
it was unclear why everything worked in Raspbian.

See issue #10 for more details.
@fhunleth fhunleth mentioned this issue Jun 9, 2017
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@fhunleth
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I did some more investigation. I can reproduce this on a Dell Precision M4700 laptop and an HP Omen. It works fine for me on an iMac. I also captured traces of the USB bus for working and non-working cases, and it looks like there's corruption in the dual-mode case that the iMac can get past but the other hardware can't. I'm including the traces below. Use the Total Phase Data Center software to view.

usb-traces.zip

The only glimmer of hope is that Raspbian somehow is able to make dual-mode work on all system, I think. It doesn't look like any special dwc2 module parameters are involved with Raspbian and experimenting with some kernel options didn't seem to do anything, though.

fhunleth added a commit that referenced this issue Jun 13, 2017
@fhunleth
Remove USB host mode support in kernel
b3bf3aa 
This makes it so that the USB port *only* works in gadget mode. It fixes
an issue where the USB connection didn't work to my laptop. Presumably,
the USB stack thinks that the port should be run in host mode. However,
it was unclear why everything worked in Raspbian.

See issue #10 for more details.
@tmecklem
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Looks maybe related: raspberrypi/linux#1997

@fhunleth
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Since we're no longer using dual mode and gadget-only mode seems pretty solid (ignoring the unrelated mDNS issue), I'm going to close this.

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@fhunleth @GregMefford @tmecklem