[Galaxy Tab 10.1 Q&A, Help & Troubleshooting] tbeauchant:
Hi Folks!

I'm a happy owner of a Galaxy Tab 10.1, and an EE engineer who frequently uses a small USB microscope while assembling boards.

I would be really happy to be able to use my Galaxy Tab as a lightweight portable screen for this microscope. This would be much more handy than having a bulky laptop stand in there.

So I've seen that the Galaxy Tab 10.1 has USB host capabilities. And after a quick verification, I've noted that the stock kernel has the uvcvideo driver builtin (the microscope is UVC compatible, actually it's a Logitech C310 hardware with added optics).

Seems like everything is in place to make it work. However when I plug the device in, I get an unrecognized USB device message popping up.

Here's the output from dmesg:

<6>[11734.027241] Board P4 : tegra_otg_en = 1<6>[11734.037361] tegra-otg tegra-otg: SUSPEND --> HOST
<6>[11734.037391] tegra-otg tegra-otg: tegra_start_host+
<4>[11734.038884] tegra_usb_phy_open() called instance :0
<6>[11734.038966] Board P4 : tegra_usb_ldo_en=1 instance=0 present regulator=1
<4>[11734.039001] utmi_phy_power_on() called. instance : 0
<6>[11734.040244] tegra-otg tegra-otg: Acc power on detect
<6>[11734.057205] Board P4 : tegra_acc_power token : (1,1) on
<4>[11734.057234] utmi_phy_clk_enable() called. instance : 0
<6>[11734.058757] tegra-ehci tegra-ehci.0: Tegra EHCI Host Controller
<6>[11734.059016] tegra-ehci tegra-ehci.0: new USB bus registered, assigned bus number 1
<6>[11734.067158] [ CONNECTOR_DRIVER (acc_notified,387) ] ACCESSORY=OTG : STATE=online
<6>[11734.087920] tegra-ehci tegra-ehci.0: irq 52, io mem 0xc5000000
<6>[11734.107159] tegra-ehci tegra-ehci.0: USB 2.0 started, EHCI 1.00
<6>[11734.107282] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
<6>[11734.107306] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
<6>[11734.107326] usb usb1: Product: Tegra EHCI Host Controller
<6>[11734.107343] usb usb1: Manufacturer: Linux 2.6.36.3 ehci_hcd
<6>[11734.107359] usb usb1: SerialNumber: tegra-ehci.0
<6>[11734.111805] hub 1-0:1.0: 1 port detected
<6>[11734.113078] tegra-otg tegra-otg: tegra_start_host-
<6>[11734.113101] host_notify: ndev name=usb_otg: from state=2 -> to state=1
<6>[11734.327059] usb 1-1: new high speed USB device using tegra-ehci and address 2
<3>[11734.592745] usb 1-1: device v046d p081b is not supported
<6>[11734.618692] host_notify: ndev name=tegra-ehci.0: from state=0 -> to state=5
<3>[11734.620877] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11734.787068] usb 1-1: new high speed USB device using tegra-ehci and address 3
<3>[11735.040504] usb 1-1: device v046d p081b is not supported
<6>[11735.076960] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11735.077029] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11735.237112] usb 1-1: new high speed USB device using tegra-ehci and address 4
<3>[11735.505766] usb 1-1: device v046d p081b is not supported
<6>[11735.528455] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11735.528541] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11735.687712] usb 1-1: new high speed USB device using tegra-ehci and address 5
<3>[11735.950203] usb 1-1: device v046d p081b is not supported
<6>[11735.978040] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11735.978125] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11736.137097] usb 1-1: new high speed USB device using tegra-ehci and address 6
<3>[11736.393178] usb 1-1: device v046d p081b is not supported
<6>[11736.417207] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11736.419203] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11736.580821] usb 1-1: new high speed USB device using tegra-ehci and address 7
<3>[11736.840702] usb 1-1: device v046d p081b is not supported
<6>[11736.866992] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11736.867057] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11737.027074] usb 1-1: new high speed USB device using tegra-ehci and address 8
<3>[11737.279441] usb 1-1: device v046d p081b is not supported
<6>[11737.306990] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11737.307086] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11737.467126] usb 1-1: new high speed USB device using tegra-ehci and address 9
<3>[11737.736913] usb 1-1: device v046d p081b is not supported
<6>[11737.758513] host_notify: ndev name=tegra-ehci.0: from state=5 -> to state=5
<3>[11737.758578] hub 1-0:1.0: unable to enumerate USB device on port 1
<6>[11737.916947] usb 1-1: new high speed USB device using tegra-ehci and address 10
app_111@android:/ $ dmesg

Then it goes on and on with the 'new device [...] unable to enumerate' messages until I unplug it.

The device is found, and early init seems to go through (VID/PID are correct) but it doesn't seem to make it to the uvcvideo driver (or the driver is rejecting it, I don't know).

I am not very savvy as regards to linux's USB stack (though I know my way around linux, having cross compiled it, and tweaked it several times for boards I design), so I'm a bit lost as to what I could further investigate to pinpoint the issue.

I am certain that uvcvideo is present (dmesg shows 'usbcore: registered new interface driver uvcvideo' after boot).

Things works fine when I plug in a USB flash drive.

Things works fine too when I plug the microscope to my linux desktop (through uvcvideo).

Any idea or advices would be greatly appreciated!

Thanks,

Theo