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nicdumzgregkh
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usb: add NO_LPM quirk for Realforce 87U Keyboard
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: [email protected] Signed-off-by: Nicolas Dumazet <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
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drivers/usb/core/quirks.c

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@@ -362,6 +362,9 @@ static const struct usb_device_id usb_quirk_list[] = {
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{ USB_DEVICE(0x0781, 0x5583), .driver_info = USB_QUIRK_NO_LPM },
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{ USB_DEVICE(0x0781, 0x5591), .driver_info = USB_QUIRK_NO_LPM },
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/* Realforce 87U Keyboard */
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{ USB_DEVICE(0x0853, 0x011b), .driver_info = USB_QUIRK_NO_LPM },
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/* M-Systems Flash Disk Pioneers */
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{ USB_DEVICE(0x08ec, 0x1000), .driver_info = USB_QUIRK_RESET_RESUME },
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