Re: [linux-uvc-devel] select-timeout errors OpenCV

[Jason P. <jn...@uw...>]

Is there a way to do a reset in software?  I guess I could wire the USB
through a relay and trip it occasionally, but that seems a rather inelegant
solution.

What would the issue be with the cabling? The camera is on a gantry robot
and an ~3-4 meter USB cable in a drag chain.  Does this error mean packets
are getting lost/garbled?  What does this error actually represent?

-J

On Thu, Oct 24, 2019 at 11:27 AM Dmitry Mikushin <dm...@ke...>
wrote:

> To my experience, many cameras run into select error sooner or later. Here
> we must elaborate that by "camera" we really mean "camera sensor +
> postprocessing chip". This postprocessing chip comes in a single package
> within the webcam. A small PCB has its own circuits (transceiver, FPGA, USB
> interface, etc.) and firmware, which is often unavailable for user
> inspection. Select error likely means that the chip/firmware has failed,
> and the webcam is put into unresponsive state. Several possible workarounds:
>
> 1) Reset the camera periodically
> 2) Ensure the USB cable is good, not affected by strong electromagnetic
> noise or intensive physical movement
> 3) Do not use USB cameras with separate postprocessing chip - instead, use
> MIPI/CSI2 cameras such as in cell phones, write your own
> postprocessing software and be fully responsible for its failures (see e.g.
> camera/driver for Raspberry Pi).
>
> Kind regards,
> - Dmitry Mikushin.
>
>
> чт, 24 окт. 2019 г. в 20:11, Jason Pitt <jn...@uw...>:
>
>> Hi-
>>
>> I'm having issues with a webcam throwing select-timeout errors after
>> several days of image acquisition.
>>
>> dmesg yields: [251952.411582] uvcvideo: Non-zero status (-71) in video
>> completion handler.
>>
>> over and over and over
>>
>> Would appreciate any help in getting this camera working more stably as
>> it's on a robotic system that needs to run for months at a time.
>>
>> thanks
>> -J
>>
>>
>> --
>> /*
>> Jason Pitt PhD                                   206.616.1193
>> Kaeberlein Lab                                   jn...@uw...
>> University of Washington
>> Department of Pathology
>> Health Sciences Building                    Box 357470
>> 1989 NE Pacific Street
>> Seattle, WA 98195
>> */
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>

-- 
/*
Jason Pitt PhD                                   206.616.1193
Kaeberlein Lab                                   jn...@uw...
University of Washington
Department of Pathology
Health Sciences Building                    Box 357470
1989 NE Pacific Street
Seattle, WA 98195
*/