Before adding this quirk, this (mechanical keyboard) device would not be recognized, logging:
new full-speed USB device number 56 using xhci_hcd unable to read config index 0 descriptor/start: -32 chopping to 0 config(s)
It would take dozens of plugging/unpuggling cycles for the keyboard to be recognized. Keyboard seems to simply work after applying this quirk.
This issue had been reported by users in two places already ([1], [2]) but nobody tried upstreaming a patch yet. After testing I believe their suggested fix (DELAY_INIT + NO_LPM + DEVICE_QUALIFIER) was probably a little overkill. I assume this particular combination was tested because it had been previously suggested in [3], but only NO_LPM seems sufficient for this device.
[1]: https://qiita.com/float168/items/fed43d540c8e2201b543 [2]: https://blog.kostic.dev/posts/making-the-realforce-87ub-work-with-usb30-on-U... [3]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1678477
--- Changes in v2: - add the entry to the right location (sorting entries by vendor/device id).
Cc: stable@vger.kernel.org Signed-off-by: Nicolas Dumazet ndumazet@google.com --- drivers/usb/core/quirks.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c index 0722d2131305..079e183cf3bf 100644 --- a/drivers/usb/core/quirks.c +++ b/drivers/usb/core/quirks.c @@ -362,6 +362,9 @@ static const struct usb_device_id usb_quirk_list[] = { { USB_DEVICE(0x0781, 0x5583), .driver_info = USB_QUIRK_NO_LPM }, { USB_DEVICE(0x0781, 0x5591), .driver_info = USB_QUIRK_NO_LPM },
+ /* Realforce 87U Keyboard */ + { USB_DEVICE(0x0853, 0x011b), .driver_info = USB_QUIRK_NO_LPM }, + /* M-Systems Flash Disk Pioneers */ { USB_DEVICE(0x08ec, 0x1000), .driver_info = USB_QUIRK_RESET_RESUME },