硬件设置
我有一台 2020 MacBook Pro 和一台 Windows 机器，插在USB 切换器使用外部 5v 电源。从转换器到 MacBook 的电缆插入贝尔金基座，MacBook 插入其中。键盘是Massdrop CTRL。
当切换器设置为 Windows 机器时，有问题的键盘在此设置下可以完美运行，但当切换到 Mac 时则不行。
我也测试了所有电缆。当跳过底座并将其插入 MacBook 时，转换器和底座之间的电缆工作正常（键盘可以使用）。
我已将问题缩小到与底座和转换器一起使用的问题。当 MacBook 仅使用底座或转换器时，键盘可以正常工作，但当两者同时使用时则不行。其他 USB 键盘在使用底座和转换器时可以正常工作。
调试
以下是我迄今为止收集的一些其他调试详细信息：
$ system_profiler SPUSBDataType当键盘插入基座时：
CTRL Keyboard:
Product ID: 0xeed2
Vendor ID: 0x04d8 (Microchip Technology Inc.)
Version: 1.01
Serial Number: 1608915629
Speed: Up to 12 Mb/s
Manufacturer: Massdrop Inc.
Location ID: 0x01420000 / 7
Current Available (mA): 500
Current Required (mA): 500
Extra Operating Current (mA): 0
当插入切换器时：
Hub:
Product ID: 0xeec5
Vendor ID: 0x04d8 (Microchip Technology Inc.)
Version: 1.01
Location ID: 0x01330000
$ dmesg | grep USB将键盘插入切换器之前和之后的差异：
[3366142.613770]: 978319.845701 AppleUSB20HubPort@01330000: AppleUSBHostPort::terminateDevice: destroying 0x04d8/eec5/0101 (IOUSBHostDevice): connect change interrupt
[3366142.615398]: 978319.847330 AppleUSB20HubPort@01330000: AppleUSBHostPort::enumerateDeviceComplete_block_invoke: enumerated stale device
[3366142.615419]: 978319.847352 IOUSBHostDevice@01330000: IOUSBHostDevice::start_block_invoke: device will not be registered for matching
[3366142.672090]: AppleUSBHostRequestCompleter::clearPipeStallThreadCall: clearStall for pipe <ptr> failed (0xe00002bc)
[3366144.672617]: 978321.904549 AppleUSB20HubPort@01330000: AppleUSBHostPort::terminateDevice: destroying 0x04d8/eec5/0101 (IOUSBHostDevice): connect change interrupt
[3366144.674165]: 978321.906097 AppleUSB20HubPort@01330000: AppleUSBHostPort::enumerateDeviceComplete_block_invoke: enumerated stale device
[3366144.674183]: 978321.906116 IOUSBHostDevice@01330000: IOUSBHostDevice::start_block_invoke: device will not be registered for matching
[3366144.731852]: AppleUSBHostRequestCompleter::clearPipeStallThreadCall: clearStall for pipe <ptr> failed (0xe00002bc)
$ ioreg -p IOUSB将键盘插入底座（工作）：
+-o Root <class IORegistryEntry, id 0x100000100, retain 26>
+-o AppleUSBVHCIBCE Root Hub Simulation@80000000 <class AppleUSBRootHubDevice, id 0x1000003e3, registered, matched, active, busy 0 (7 ms), retain 15>
| +-o Headset@80400000 <class AppleUSBDevice, id 0x1000003e5, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple T2 Controller@80100000 <class AppleUSBDevice, id 0x1000003eb, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Backlight@80700000 <class AppleUSBDevice, id 0x1000003f1, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o FaceTime HD Camera (Built-in)@80200000 <class AppleUSBDevice, id 0x1000003f8, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Display@80600000 <class AppleUSBDevice, id 0x100000401, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Ambient Light Sensor@80300000 <class AppleUSBDevice, id 0x10000040f, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple Internal Keyboard / Trackpad@80500000 <class AppleUSBDevice, id 0x100105c59, registered, matched, active, busy 0 (2 ms), retain 19>
+-o AppleUSBXHCI Root Hub Simulation@00000000 <class AppleUSBRootHubDevice, id 0x10008f0dc, registered, matched, active, busy 0 (0 ms), retain 8>
+-o AppleUSBXHCI Root Hub Simulation@14000000 <class AppleUSBRootHubDevice, id 0x10009c5ff, registered, matched, active, busy 0 (1 ms), retain 8>
+-o AppleUSBXHCI Root Hub Simulation@01000000 <class AppleUSBRootHubDevice, id 0x100105acb, registered, matched, active, busy 0 (1 ms), retain 11>
+-o USB3.1 Hub@01100000 <class AppleUSBDevice, id 0x1001064ee, registered, matched, active, busy 0 (0 ms), retain 11>
+-o USB2.1 Hub@01300000 <class AppleUSBDevice, id 0x100106505, registered, matched, active, busy 0 (0 ms), retain 14>
| +-o Razer Naga Pro@01340000 <class AppleUSBDevice, id 0x10010651d, registered, matched, active, busy 0 (3 ms), retain 19>
| +-o G533 Gaming Headset@01310000 <class AppleUSBDevice, id 0x10010655a, registered, matched, active, busy 0 (1 ms), retain 17>
| +-o KM360 MX@01320000 <class AppleUSBDevice, id 0x100106594, registered, matched, active, busy 0 (1 ms), retain 13>
+-o IOUSBHostDevice@01400000 <class AppleUSBDevice, id 0x1001071a9, registered, matched, active, busy 0 (0 ms), retain 12>
+-o CTRL Keyboard@01420000 <class AppleUSBDevice, id 0x1001071ba, registered, matched, active, busy 0 (3 ms), retain 17>
当插入交换集线器时：
+-o Root <class IORegistryEntry, id 0x100000100, retain 26>
+-o AppleUSBVHCIBCE Root Hub Simulation@80000000 <class AppleUSBRootHubDevice, id 0x1000003e3, registered, matched, active, busy 0 (7 ms), retain 15>
| +-o Headset@80400000 <class AppleUSBDevice, id 0x1000003e5, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple T2 Controller@80100000 <class AppleUSBDevice, id 0x1000003eb, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Backlight@80700000 <class AppleUSBDevice, id 0x1000003f1, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o FaceTime HD Camera (Built-in)@80200000 <class AppleUSBDevice, id 0x1000003f8, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Display@80600000 <class AppleUSBDevice, id 0x100000401, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Ambient Light Sensor@80300000 <class AppleUSBDevice, id 0x10000040f, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple Internal Keyboard / Trackpad@80500000 <class AppleUSBDevice, id 0x100105c59, registered, matched, active, busy 0 (2 ms), retain 19>
+-o AppleUSBXHCI Root Hub Simulation@00000000 <class AppleUSBRootHubDevice, id 0x10008f0dc, registered, matched, active, busy 0 (0 ms), retain 8>
+-o AppleUSBXHCI Root Hub Simulation@14000000 <class AppleUSBRootHubDevice, id 0x10009c5ff, registered, matched, active, busy 0 (1 ms), retain 8>
+-o AppleUSBXHCI Root Hub Simulation@01000000 <class AppleUSBRootHubDevice, id 0x100105acb, registered, matched, active, busy 0 (1 ms), retain 10>
+-o USB3.1 Hub@01100000 <class AppleUSBDevice, id 0x1001064ee, registered, matched, active, busy 0 (0 ms), retain 11>
+-o USB2.1 Hub@01300000 <class AppleUSBDevice, id 0x100106505, registered, matched, active, busy 0 (0 ms), retain 14>
+-o Razer Naga Pro@01340000 <class AppleUSBDevice, id 0x10010651d, registered, matched, active, busy 0 (3 ms), retain 19>
+-o G533 Gaming Headset@01310000 <class AppleUSBDevice, id 0x10010655a, registered, matched, active, busy 0 (1 ms), retain 17>
+-o KM360 MX@01320000 <class AppleUSBDevice, id 0x100106594, registered, matched, active, busy 0 (1 ms), retain 13>
将集线器连接到基座电缆并将其直接放入 MacBook 中以代替基座（键盘在此配置下可用）：
+-o Root <class IORegistryEntry, id 0x100000100, retain 25>
+-o AppleUSBVHCIBCE Root Hub Simulation@80000000 <class AppleUSBRootHubDevice, id 0x1000003e3, registered, matched, active, busy 0 (7 ms), retain 15>
| +-o Headset@80400000 <class AppleUSBDevice, id 0x1000003e5, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple T2 Controller@80100000 <class AppleUSBDevice, id 0x1000003eb, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Backlight@80700000 <class AppleUSBDevice, id 0x1000003f1, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o FaceTime HD Camera (Built-in)@80200000 <class AppleUSBDevice, id 0x1000003f8, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Touch Bar Display@80600000 <class AppleUSBDevice, id 0x100000401, registered, matched, active, busy 0 (0 ms), retain 13>
| +-o Ambient Light Sensor@80300000 <class AppleUSBDevice, id 0x10000040f, registered, matched, active, busy 0 (0 ms), retain 11>
| +-o Apple Internal Keyboard / Trackpad@80500000 <class AppleUSBDevice, id 0x100105c59, registered, matched, active, busy 0 (2 ms), retain 19>
+-o AppleUSBXHCI Root Hub Simulation@00000000 <class AppleUSBRootHubDevice, id 0x10008f0dc, registered, matched, active, busy 0 (0 ms), retain 8>
+-o AppleUSBXHCI Root Hub Simulation@14000000 <class AppleUSBRootHubDevice, id 0x10009c5ff, registered, matched, active, busy 0 (1 ms), retain 8>
目前我对 USB 还不够熟悉，不知道如何继续。
答案1
USB 切换器违反了非常基本的 USB 规范，使用 USB-A 端口作为输入，几乎可以肯定他们在其他地方也违反了规范。它无法正常工作，很可能是因为他们没有遵循要求的规范。如果有人将 USB 切换器附带的 USB-A 转 USB-A 电缆与随附的 USB 切换器以外的其他设备一起使用，则可能会引起火灾。在产品说明中，他们警告说该设备可能会干扰 2.4 GHz Wi-Fi 和蓝牙，这是设计不良的另一个迹象。这个开关坏了，如果可以的话，请将其寄回以获得退款。不要再买类似的开关了，因为它也会一样坏。设计有问题。
根据您插入设备的方式，您可能会使用交换机附带的电缆（两端都带有 USB-A 的电缆）损坏计算机或集线器。该电缆可能会使 USB 端口供电短路。请不要再用它做实验了。扔掉它或寄回。
USB 规范要求连接到主机的端口必须是 USB-B/母头、USB-C/母头、带有 USB-A 或 USB-C 公头的固定电缆或专有连接器。现在 USB 设备上很少看到专有连接器，但在 USB-C 出现之前，它们在手机和其他便携式电子设备上很常见，通常是一些薄而扁平的宽连接器，带有弹簧夹将其固定到位。设备端口应该是母头 USB-A 或 USB-C，但违反此规范是不寻常的，因为任何其他方式都会使插入设备变得困难。