This is a note to let you know that I've just added the patch titled usb: add NO_LPM quirk for Realforce 87U Keyboard to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-add-no_lpm-quirk-for-realforce-87u-keyboard.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 181135bb20dcb184edd89817831b888eb8132741 Mon Sep 17 00:00:00 2001 From: Nicolas Dumazet <ndumazet@xxxxxxxxxx> Date: Wed, 9 Nov 2022 13:29:46 +0100 Subject: usb: add NO_LPM quirk for Realforce 87U Keyboard From: Nicolas Dumazet <ndumazet@xxxxxxxxxx> commit 181135bb20dcb184edd89817831b888eb8132741 upstream. 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-Ubuntu/ [3]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1678477 Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Nicolas Dumazet <ndumazet@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221109122946.706036-1-ndumazet@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/quirks.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/core/quirks.c +++ b/drivers/usb/core/quirks.c @@ -362,6 +362,9 @@ static const struct usb_device_id usb_qu { 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 }, Patches currently in stable-queue which might be from ndumazet@xxxxxxxxxx are queue-4.19/usb-add-no_lpm-quirk-for-realforce-87u-keyboard.patch