Re: [PATCH v5 2/3] media: uvcvideo: add UVC_QUIRK_CTRL_THROTTLE for fragile firmware

Jeffrey Hein
2026-04-10T00:24:49Z

One more thing -- you mentioned referencing an lsusb from
linux-hardware.org for an "identical(?) device". Here is the actual
lsusb -vv from our device, confirming the wBytesPerInterval mismatch
you found.

EP5 IN (interrupt) from raw SS Endpoint Companion descriptor:

Endpoint Descriptor:
bEndpointAddress 0x85 EP 5 IN
bmAttributes 3 (Interrupt)
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 8
SS Endpoint Companion:
bMaxBurst 0
bmAttributes 0x00
wBytesPerInterval 8

So wBytesPerInterval (8) is indeed 8x smaller than wMaxPacketSize (64),
matching what you saw in the third-party listing.

Note that lsusb -vv does not decode wBytesPerInterval for this
endpoint -- the value above was parsed from the raw descriptor bytes
in sysfs. The full lsusb -vv (934 lines) is now in the repo:

https://github.com/jphein/kiyo-xhci-fix/blob/main/kernel-patches/crash-evidence/lsusb-vv-kiyo-pro.txt

I will follow up with the test results from your patch.

JP