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Date:      Mon, 20 Jul 2026 14:24:30 +0200
From:      Baptiste Daroussin <bapt@FreeBSD.org>
To:        Nilton Jose Rizzo <rizzo@rizzo.eng.br>
Cc:        freebsd-current@freebsd.org
Subject:   Re: uvideo not wrok fine
Message-ID:  <al4TI4T7VnM03WmN@b.nours.eu>
In-Reply-To: <5f70832a-a9fc-4cc2-85c9-143690e56da1@rizzo.eng.br>
References:  <9fe285ad-e92c-468c-a3b1-4539acef7064@rizzo.eng.br> <22C82D84-9DA8-473F-88A9-7DAE88F234BD@nours.eu> <43193a69-cd0f-474a-9626-44421ad39316@rizzo.eng.br> <18807C4E-3294-4A9D-A8A4-B9D5989B8F79@nours.eu> <5f70832a-a9fc-4cc2-85c9-143690e56da1@rizzo.eng.br>

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On Sun 19 Jul 14:03, Nilton Jose Rizzo wrote:
> Em 19/07/2026 13:49, Baptiste Daroussin escreveu:
> > 
> > Le 18 juillet 2026 23:45:58 GMT+02:00, Nilton Jose Rizzo<rizzo@rizzo.eng.br> a écrit :
> > > Em 18/07/2026 02:36, Baptiste Daroussin escreveu:
> > > > Le 14 juillet 2026 01:42:07 GMT+02:00, Nilton Jose Rizzo<rizzo@rizzo.eng.br> a écrit :
> > > > > Hi all,
> > > > > 
> > > > > I upgraded my desktop last weekend and decided to try the new *uvideo*driver from OpenBSD.
> > > > > 
> > > > > When I run |pwcview|, the image is displayed incorrectly: it is horizontally duplicated and shows interlaced lines.
> > > > > 
> > > > > If I switch back to |webcamd|, the webcam works normally.
> > > > > 
> > > > > I also tested it with *Google Meet*and *Jitsi Meet*in Firefox.
> > > > > 
> > > > > On Google Meet, I receive a warning indicating that my webcam is not functioning properly.
> > > > > 
> > > > > Has anyone experienced this issue or have any suggestions on how to troubleshoot it?
> > > > > 
> > > > > My web cam is HD Pro C920 USB
> > > > > 
> > > > > ugen0.2: <HD Pro Webcam C920 Logitech, Inc.> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (500mA)
> > > > > 
> > > > > $ usbconfig -v -d ugen0.2
> > > > > ugen0.2: <HD Pro Webcam C920 Logitech, Inc.> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (500mA)
> > > > > ugen0.2.2: uaudio0: <vendor 0x046d HD Pro Webcam C920, class 239/2, rev 2.00/0.11, addr 3>
> > > > > 
> > > > >     bLength = 0x0012
> > > > >     bDescriptorType = 0x0001
> > > > >     bcdUSB = 0x0200
> > > > >     bDeviceClass = 0x00ef  <Miscellaneous device>
> > > > >     bDeviceSubClass = 0x0002
> > > > >     bDeviceProtocol = 0x0001
> > > > >     bMaxPacketSize0 = 0x0040
> > > > >     idVendor = 0x046d
> > > > >     idProduct = 0x082d
> > > > >     bcdDevice = 0x0011
> > > > >     iManufacturer = 0x0000  <no string>
> > > > >     iProduct = 0x0002  <HD Pro Webcam C920>
> > > > >     iSerialNumber = 0x0001  <1BC69C1F>
> > > > >     bNumConfigurations = 0x0001
> > > > > 
> > > > > When uvideo load, show this message
> > > > > 
> > > > > uvideo0 on uhub1
> > > > > uvideo0: <vendor 0x046d HD Pro Webcam C920, class 239/2, rev 2.00/0.11, addr 3> on usbus0
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: too many PU descriptors found!
> > > > > uvideo0: 3 format(s), iface_index=1, endpoint=0x81, psize=3060, isoc
> > > > > uvideo0: default format: pixfmt=0x56595559, 640x480, max_fbuf=4147200
> > > > > uvideo0: UVC camera on /dev/video0
> > > > > 
> > > > > 
> > > > try updating UVIDEO_MAX_PU and UVIDEO_MAX_CT from 8 to 32.
> > > > 
> > > > in sys/dev/usb/video/uvideo.c
> > > > 
> > > > best regards,
> > > > Bapt
> > > I change these values, PU warnings was gone.
> > > 
> > > My Webcam not work fine yet.
> > > 
> > > See this jpeg screenshot from pwcview using default values to fps and resolution (sif).
> > > 
> > > https://imgur.com/a/YG89hK5
> > > 
> > > 
> > > ugen0.2: <vendor 0x046d HD Pro Webcam C920> at usbus0
> > > uvideo0 on uhub1
> > > uvideo0: <vendor 0x046d HD Pro Webcam C920, class 239/2, rev 2.00/0.11, addr 3> on usbus0
> > > uvideo0: 3 format(s), iface_index=1, endpoint=0x81, psize=3060, isoc
> > > uvideo0: default format: pixfmt=0x56595559, 640x480, max_fbuf=4147200
> > > uvideo0: UVC camera on /dev/video0
> > > uaudio0 on uhub1
> > > uaudio0: <vendor 0x046d HD Pro Webcam C920, class 239/2, rev 2.00/0.11, addr 3> on usbus0
> > > uaudio0: No playback.
> > > uaudio0: Record[0]: 32000 Hz, 2 ch, 16-bit S-LE PCM format, 2x4ms buffer. (selected)
> > > uaudio0: Record[0]: 24000 Hz, 2 ch, 16-bit S-LE PCM format, 2x4ms buffer.
> > > uaudio0: Record[0]: 16000 Hz, 2 ch, 16-bit S-LE PCM format, 2x4ms buffer.
> > > uaudio0: No MIDI sequencer.
> > > pcm6 on uaudio0
> > > uaudio0: No HID volume keys found.
> > > uvideo0: stream open: nframes=51, psize=3060, maxVideoFrameSize=153600, maxPayloadSize=800, alt=11, isoc
> > > uvideo0: stream open: nframes=51, psize=3060, maxVideoFrameSize=153600, maxPayloadSize=800, alt=11, isoc
> > > 
> > > 
> > > 
> > on linux it has quirks for this model, I need to implement some. I ll come back with a patch soon
> > 
> > bapt
> 
> I'd be happy to help improve this driver by providing more information about
> this camera. Let me know what information would be useful.
> 
> Thank you Baptiste.
> 
> -- 
> **************************
> * Dr. Nilton Jose Rizzo  *
> * Engenheiro Eletrônico  *
> * Doutor pela COPPE/UFRJ *
> * Telegram: @njrizzo     *
> **************************

I have pushed the quirks infrastructure from openbsd, can you try the following
patch on top of it? this is quirks I found for your model in linux uvc driver:

https://people.freebsd.org/~bapt/0001-uvideo-add-quirks-for-Logitech-C920-webcams.patch

Best regards,
Bapt


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