Driver for webcam: different behaviour with USB and USB via ExpressCard

SuSE_Lamer · 12-11-2021, 10:47 AM

Hello,

unfortunately, I am not very familiar with kernel interna if Linux, therefore I have one question to experts: is it possible that one driver (UVC, to be more precise) is not loaded when I plug my web-cam via "ordinary" USB port on my laptop, but is loaded when I plug my web-cam via ExpressCard-based USB-hub?

Here is my situation: I have web-cam (Hercules DualPix Chat and SHow), which is supported by "uvc" driver. When I plug it via USB port, it does not work. But it works, when I use USB-3.0-hub in ExpressCard-slot.

Thanks in advance,
Andrey

ondoho · 12-12-2021, 06:19 AM

https://www.linuxquestions.org/quest...h-dmesg-38682/

SuSE_Lamer · 12-19-2021, 01:27 PM

Hello
thanks for the hint.

Quote:

Originally Posted by ondoho

https://www.linuxquestions.org/quest...h-dmesg-38682/

Here is an output of dmesg when cam connected to built-in laptop USB port - and not usable by software

Code:

[10445.535454] usb 1-3: new high-speed USB device number 7 using ehci-pci
[10445.703560] usb 1-3: New USB device found, idVendor=06f8, idProduct=3007, bcdDevice= 1.00
[10445.703567] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[10445.703571] usb 1-3: Product: Hercules Dualpix Chat and Show Webcam
[10445.703576] usb 1-3: Manufacturer: Guillemot Corporation
[10445.706287] usb 1-3: 3:1: cannot get freq at ep 0x84
[10445.918277] media: Linux media interface: v0.10
[10445.957486] videodev: Linux video capture interface: v2.00
[10446.008036] uvcvideo: Found UVC 1.00 device Hercules Dualpix Chat and Show Webcam (06f8:3007)
[10446.009776] uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[10446.010908] input: Hercules Dualpix Chat and Show  as /devices/pci0000:00/0000:00:1a.7/usb1/1-3/1-3:1.0/input/input30
[10446.011202] usbcore: registered new interface driver uvcvideo
[10446.011203] USB Video Class driver (1.1.1)
[10446.089655] usb 1-3: 3:1: cannot get freq at ep 0x84
[10446.154032] usb 1-3: 3:1: cannot get freq at ep 0x84
[10446.172040] retire_capture_urb: 13 callbacks suppressed

And here is an output of dmesg when cam connected via USB 3.0 - port via ExpressCard (and software can use cam):

Code:

[10649.843486] usb 8-2: new high-speed USB device number 4 using xhci_hcd
[10649.997882] usb 8-2: New USB device found, idVendor=06f8, idProduct=3007, bcdDevice= 1.00
[10649.997890] usb 8-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[10649.997894] usb 8-2: Product: Hercules Dualpix Chat and Show Webcam
[10649.997899] usb 8-2: Manufacturer: Guillemot Corporation
[10650.007978] uvcvideo: Found UVC 1.00 device Hercules Dualpix Chat and Show Webcam (06f8:3007)
[10650.015977] uvcvideo: UVC non compliance - GET_DEF(PROBE) not supported. Enabling workaround.
[10650.019107] input: Hercules Dualpix Chat and Show  as /devices/pci0000:00/0000:00:1c.3/0000:05:00.0/usb8/8-2/8-2:1.0/input/input31
[10650.023988] usb 8-2: 3:1: cannot get freq at ep 0x84
[10650.284940] usb 8-2: 3:1: cannot get freq at ep 0x84
[10650.346571] usb 8-2: 3:1: cannot get freq at ep 0x84

The output is different, I see it. But I would appreciate when somebody gives me a hint, what's wrong with a built-in USB port.

Regards,
Andrey

computersavvy · 12-19-2021, 09:26 PM

Just a guess that I cannot test, but this comes to mind.

1. The express card is usb 3.0
2. What is the built-in usb? 2.0 or 3.0
3. What is the camera built for? 2.0 or 3.0

My guess, as I said.
I suspect the built in USB may be 2.0 and the camera will not work on a 2.0 port so it does not get properly configured.

Just my

SuSE_Lamer · 12-20-2021, 08:13 AM

Hello,

Quote:

Originally Posted by computersavvy

Just a guess that I cannot test, but this comes to mind.

1. The express card is usb 3.0
2. What is the built-in usb? 2.0 or 3.0
3. What is the camera built for? 2.0 or 3.0

My guess, as I said.
I suspect the built in USB may be 2.0 and the camera will not work on a 2.0 port so it does not get properly configured.

Just my

ExpressCard is USB 3.0, built in slot supports 2.0. The cam itself is rather old, I would say - 2.0 as highest. Perhaps, even 1.1.

As far as I know, built-in and ExpressCard-USB are processed by different events. Built-in is an USB-event, and ExpressCard-USB is actually a PCI event. Can it be a reason?

Regards,
Andrey

ondoho · 12-24-2021, 03:17 AM

Quote:

Originally Posted by SuSE_Lamer

As far as I know, built-in and ExpressCard-USB are processed by different events. Built-in is an USB-event, and ExpressCard-USB is actually a PCI event.

I'm not sure how this works low-level, but the dmesg output is clear: both times the device is registered as a USB device.
It uses 2 different USB drivers in the 2 outputs:

when xhci_hcd is loaded (which is capable of USB 1.x, 2.x and 3.x.) it works
when ehci-pci is loaded (which is capable of USB 1.x and 2.0 afaics) it doesn't work

How old is this laptop and what do you know about its USB ports? If it still has USB 1.x only ports it must be very old indeed, and I'd just live with the current solution.

If you want to pursue this further we also need more info about your OS and kernel version.

If you want to get confused, read this

SuSE_Lamer · 12-25-2021, 03:54 PM

Hello ondoho,

Quote:

Originally Posted by ondoho

I'm not sure how this works low-level, but the dmesg output is clear: both times the device is registered as a USB device.
It uses 2 different USB drivers in the 2 outputs:

when xhci_hcd is loaded (which is capable of USB 1.x, 2.x and 3.x.) it works
when ehci-pci is loaded (which is capable of USB 1.x and 2.0 afaics) it doesn't work

How old is this laptop and what do you know about its USB ports? If it still has USB 1.x only ports it must be very old indeed, and I'd just live with the current solution.

If you want to pursue this further we also need more info about your OS and kernel version.

If you want to get confused, read this

my laptop is Thinkpad R61, it has USB 2.0 ports. Funny thing is that even built-in ports do not fail always, but from time. Sometimes the cam is recognized, and sometimes is not.

I could not detect certain pattern for it. Standby, first plug in - I tried everything, but it is too random... I think, I will stay with "Expresscard"-solution, because an effort to find a solution here seems to be too high - comparing to the importance of the problem.

Thanks for the hints,
Andrey