[Bug 222229] New: HID: usbhid: Razer DeathStalker Essential 2014 (1532:011f) 51.2s EP0 initialization timeout (-110), dead LEDs, and hotplug failure

[Bug 222229] New: HID: usbhid: Razer DeathStalker Essential 2014 (1532:011f) 51.2s EP0 initialization timeout (-110), dead LEDs, and hotplug failure

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222229

            Bug ID: 222229
           Summary: HID: usbhid: Razer DeathStalker Essential 2014
                    (1532:011f) 51.2s EP0 initialization timeout (-110),
                    dead LEDs, and hotplug failure
           Product: Drivers
           Version: 2.5
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: USB
          Assignee: drivers_usb@kernel-bugs.kernel.org
          Reporter: pierre.jap@gmail.com
        Regression: No

Overview
========
When booting with or hot-plugging a Razer DeathStalker Essential 2014 keyboard
(USB ID 1532:011f), USB HID enumeration hangs for 51.2 seconds (`usbhid: can't
add hid device: -110` on interfaces 1.1 and 1.2), status LEDs (NumLock /
CapsLock / ScrollLock) fail to light (`usb_submit_urb(ctrl) failed: -1`), and
unplugging/replugging leaves the keyboard completely unresponsive on ~75% of
attempts.

dmesg Output (Unpatched)
========================
usb 3-6.2: new full-speed USB device number 5 using xhci_hcd
usb 3-6.2: New USB device found, idVendor=1532, idProduct=011f, bcdDevice= 2.00
usb 3-6.2: Product: Razer DeathStalker Essential 2014
usb 3-6.2: Manufacturer: Razer
input: Razer Razer DeathStalker Essential 2014 as /devices/.../input/input5
hid-generic 0003:1532:011F.0001: input,hidraw0: USB HID v1.11 Keyboard [Razer
Razer DeathStalker Essential 2014] on usb-.../input0
usbhid 3-6.2:1.0: usb_submit_urb(ctrl) failed: -1
usbhid 3-6.2:1.1: can't add hid device: -110
usbhid 3-6.2:1.1: probe with driver usbhid failed with error -110
usbhid 3-6.2:1.2: can't add hid device: -110
usbhid 3-6.2:1.2: probe with driver usbhid failed with error -110

Root Cause Analysis (Verified via usbmon & EP0 probing)
=======================================================
The Razer DeathStalker Essential 2014 exposes 3 USB HID interfaces sharing
Control Endpoint 0 (EP0, bMaxPacketSize0 = 64):
- Interface 0 (1.0): Boot Keyboard + LEDs (61-byte report descriptor, ep_81 IN)
- Interface 1 (1.1): NKRO Keyboard + Consumer/System Control (179-byte report
descriptor, ep_82 IN)
- Interface 2 (1.2): Virtual Mouse + 90-byte Vendor Feature Report (94-byte
report descriptor, ep_83 IN)

Three interacting firmware/kernel behaviors wedge the keyboard
microcontroller's EP0 state machine on Linux:

1. `usbhid_init_reports()` (`HID_REQ_GET_REPORT`) on Interface 0:
   Sending `HID_REQ_GET_REPORT` (0x01) over EP0 during `usbhid_start()`
destabilizes the MCU. Applying `HID_QUIRK_NO_INIT_REPORTS | HID_QUIRK_NOGET`
prevents `usbhid_init_reports()` from probing reports on EP0.

2. Dirty EP0 state after class `GET_DESCRIPTOR(HID_DT_REPORT)` (`bmRequestType
= 0x81`):
   After `usbhid_parse()` reads the 61-byte `HID_DT_REPORT` descriptor on
Interface 0 (`bmRequestType = 0x81`), the MCU leaves its EP0 parser in a state
where an immediate class-specific `HID_REQ_SET_REPORT` (`bmRequestType = 0x21`,
bRequest = 0x09 — used to set the NumLock LED) or `HID_REQ_SET_IDLE` either
fails or locks up EP0.
   Issuing a standard 18-byte `GET_DESCRIPTOR(USB_DT_DEVICE)` (`bmRequestType =
0x80`, bRequest = 0x06, wValue = 0x0100) on EP0 immediately before and
immediately after `usbhid_parse()` resets the MCU's EP0 state machine cleanly.

3. Asynchronous `hdev->led_work` (`SET_REPORT`) race vs. Interface 1.1
enumeration:
   At the end of Interface 0's input registration (`hidinput_connect()` ->
`input_register_device()` -> `input_leds_connect()`), the kernel schedules
`hdev->led_work` (`hidinput_led_worker`) asynchronously on `system_wq` to send
`HID_REQ_SET_REPORT` over EP0 at the exact same moment
`usb_set_configuration()` moves on to probe Interface 1 (1.1) on EP0.
   Additionally, on Interface 1's first 179-byte (`0xb3`)
`GET_DESCRIPTOR(HID_DT_REPORT)` request, the MCU occasionally drops one 64-byte
packet and returns 115 bytes (`179 - 64`). When `usbhid_parse()` immediately
retries without an intervening `USB_DT_DEVICE` descriptor read, EP0 stops
responding for 2 x 25.6s = 51.2s (`-ETIMEDOUT`).

Verified Fix / Proof of Concept
===============================
Flushing `hdev->led_work` before probing secondary interfaces, applying
`HID_QUIRK_NO_INIT_REPORTS | HID_QUIRK_NOGET`, and issuing an 18-byte
`GET_DESCRIPTOR(USB_DT_DEVICE)` on EP0 between HID descriptor reads reduces
initialization time from 51.2s to < 0.2s, makes hotplugging 100% reliable, and
restores NumLock/CapsLock LEDs across all 3 interfaces (`1.0`, `1.1`, `1.2`).

Full working out-of-tree DKMS module demonstrating the fix:
https://github.com/Djkawada/razer-deathstalker-linux-fix

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