I recently purchased a Logitech 1080p Pro Stream webcam, and I couldn't determine why it kept reporting
I have no idea why the OS would expect more data than it received, but I knew this was probably the reason multimedia/webcamd wasn't working, no matter what I did. It turns out that simply increasing the amount of time to receive data fixed my problem, which is what the diffs linked below do. It's strange how a PR for a different error led me to a commit that solved my own error, but you won't see me complaining! 
While meant for 11-STABLE and 12-STABLE, the patch works on my 12.1-RELEASE-p10 system as well. It's too late to see the fix incorporated into 12.2-RELEASE if the comments in the linked PR are correct, and 13.0-RELEASE is expected in less than 6 months anyway. Unfortunately, this means that you may need to build your own kernel for a while or continue with a non-working webcam until you upgrade to a supported version that contains the fix.
PR 248926 – Logitech HD Pro Webcam C920 USB_ERR_TIMEOUT
12-STABLE diff
11-STABLE diff
Edit:
If you're in need of a way to test your webcam, multimedia/pwcview is useful for offline testing, and I found webcamtests.com quite useful for testing my webcam in a browser.
Code:
usb_alloc_device: Failure selecting configuration index 0:USB_ERR_SHORT_XFER, port 4, addr 4 (ignored)While meant for 11-STABLE and 12-STABLE, the patch works on my 12.1-RELEASE-p10 system as well. It's too late to see the fix incorporated into 12.2-RELEASE if the comments in the linked PR are correct, and 13.0-RELEASE is expected in less than 6 months anyway. Unfortunately, this means that you may need to build your own kernel for a while or continue with a non-working webcam until you upgrade to a supported version that contains the fix.
PR 248926 – Logitech HD Pro Webcam C920 USB_ERR_TIMEOUT
12-STABLE diff
11-STABLE diff
Edit:
If you're in need of a way to test your webcam, multimedia/pwcview is useful for offline testing, and I found webcamtests.com quite useful for testing my webcam in a browser.