Thank you very much for your reply. So I tried to see if there's any difference between the two devices. I can see that the one didn't get enabled by default has an extra interface with 0 for the two attributes. But does that matter? Because if it does, shouldn't the mouse interface prevents the other one to get enabled by default as well? Seems to me the keyboard interface is the first interface for both devices: [tom@localhost ~]$ cat /sys/devices/pci0000\:00/0000\:00\:14.0/usb3/3-13/3-13\:1.0/bInterfaceSubClass 01 [tom@localhost ~]$ cat /sys/devices/pci0000\:00/0000\:00\:14.0/usb3/3-13/3-13\:1.0/bInterfaceProtocol 01 [tom@localhost ~]$ cat /sys/devices/pci0000\:00/0000\:00\:14.0/usb3/3-14/3-14\:1.0/bInterfaceSubClass 01 [tom@localhost ~]$ cat /sys/devices/pci0000\:00/0000\:00\:14.0/usb3/3-14/3-14\:1.0/bInterfaceProtocol 01 [tom@localhost ~]$ diff <(sudo lsusb -v -s 003:002) <(sudo lsusb -v -s 003:003) can't get device qualifier: Resource temporarily unavailable can't get debug descriptor: Resource temporarily unavailable can't get device qualifier: Resource temporarily unavailable can't get debug descriptor: Resource temporarily unavailable 2c2 < Bus 003 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver --- > Bus 003 Device 003: ID 046d:c52e Logitech, Inc. MK260 Wireless Combo Receiver 12,13c12,13 < idProduct 0xc52b Unifying Receiver < bcdDevice 12.01 --- > idProduct 0xc52e MK260 Wireless Combo Receiver > bcdDevice 15.00 21,22c21,22 < wTotalLength 84 < bNumInterfaces 3 --- > wTotalLength 59 > bNumInterfaces 2 24c24 < iConfiguration 4 RQR12.01_B0019 --- > iConfiguration 4 RQR15.00_B0048 76c76 < wDescriptorLength 148 --- > wDescriptorLength 177 87,117c87 < wMaxPacketSize 0x0008 1x 8 bytes < bInterval 2 < Interface Descriptor: < bLength 9 < bDescriptorType 4 < bInterfaceNumber 2 < bAlternateSetting 0 < bNumEndpoints 1 < bInterfaceClass 3 Human Interface Device < bInterfaceSubClass 0 < bInterfaceProtocol 0 < iInterface 0 < HID Device Descriptor: < bLength 9 < bDescriptorType 33 < bcdHID 1.11 < bCountryCode 0 Not supported < bNumDescriptors 1 < bDescriptorType 34 Report < wDescriptorLength 98 < Report Descriptors: < ** UNAVAILABLE ** < Endpoint Descriptor: < bLength 7 < bDescriptorType 5 < bEndpointAddress 0x83 EP 3 IN < bmAttributes 3 < Transfer Type Interrupt < Synch Type None < Usage Type Data < wMaxPacketSize 0x0020 1x 32 bytes --- > wMaxPacketSize 0x0014 1x 20 bytes On 21 April 2015 at 01:41, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 21 Apr 2015, Tom Yan wrote: > >> I have the following two USB wireless mouse/keyboard receivers: >> >> logitech-djreceiver 0003:046D:C52B.0003: hiddev0,hidraw0: USB HID >> v1.11 Device [Logitech USB Receiver] on usb-0000:00:14.0-13/input2 >> hid-generic 0003:046D:C52E.0005: input,hidraw2: USB HID v1.11 Keyboard >> [Logitech USB Receiver] on usb-0000:00:14.0-14/input0 >> >> The default values in their power/wakeup: >> [tom@localhost ~]$ cat /sys/bus/usb/devices/3-13/power/wakeup >> disabled >> [tom@localhost ~]$ cat /sys/bus/usb/devices/3-14/power/wakeup >> enabled >> >> According to https://www.kernel.org/doc/Documentation/usb/power-management.txt: >> >> power/wakeup >> >> This file is empty if the device does not support >> remote wakeup. Otherwise the file contains either the >> word "enabled" or the word "disabled", ... >> >> My question is, which part of the kernel or system determines the >> default value? When I had a quick look on the source of the two driver >> modules, I couldn't find any code related. So what caused the >> difference? >> >> P.S. I have no udev rule related to power/wakeup, which is the case I >> am asking about. >> >> [tom@localhost ~]$ cd /etc/udev/rules.d/ >> [tom@localhost rules.d]$ grep wakeup * >> grep: *: No such file or directory >> [tom@localhost rules.d]$ cd /lib/udev/rules.d/ >> [tom@localhost rules.d]$ grep wakeup * >> 42-usb-hid-pm.rules:# advertise remote wakeup support but don't >> actually implement >> 42-usb-hid-pm.rules:# remote wakeup is working. > > This is from usbhid_start() in drivers/hid/usbhid/hid-core.c: > > /* Some keyboards don't work until their LEDs have been set. > * Since BIOSes do set the LEDs, it must be safe for any device > * that supports the keyboard boot protocol. > * In addition, enable remote wakeup by default for all keyboard > * devices supporting the boot protocol. > */ > if (interface->desc.bInterfaceSubClass == USB_INTERFACE_SUBCLASS_BOOT && > interface->desc.bInterfaceProtocol == > USB_INTERFACE_PROTOCOL_KEYBOARD) { > usbhid_set_leds(hid); > device_set_wakeup_enable(&dev->dev, 1); > } > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
