On Mon, 13 Apr 2009, Philipp Wagner wrote: > Hi, > > Alan Stern schrieb: > > Just as a hint: You can get more information about the device (i.e., > > you can get the report descriptors) by doing: > > > > rmmod usbhid > > lsusb -v > > modprobe usbhid > > Thank you Alan, that's useful indeed. I'm still reading more about the > USB specification in order to fully understand the report descriptor, > but I'd be thankful if somebody finds some time to look over it and give > me a hint where to start to get a working driver. > > Item(Global): Usage Page, data= [ 0x0c ] 12 > Consumer > Item(Local ): Usage, data= [ 0x01 ] 1 > Consumer Control > Item(Main ): Collection, data= [ 0x01 ] 1 > Application > Item(Global): Usage Page, data= [ 0x0c ] 12 > Consumer > Item(Local ): Usage, data= [ 0xe9 ] 233 > Volume Increment > Item(Global): Usage Page, data= [ 0x0c ] 12 > Consumer > Item(Local ): Usage, data= [ 0xea ] 234 > Volume Decrement > Item(Global): Logical Minimum, data= [ 0x00 ] 0 > Item(Global): Logical Maximum, data= [ 0x01 ] 1 > Item(Global): Report Count, data= [ 0x02 ] 2 > Item(Global): Report Size, data= [ 0x01 ] 1 > Item(Main ): Input, data= [ 0x42 ] 66 > Data Variable Absolute No_Wrap Linear > Preferred_State Null_State Non_Volatile Bitfield > Item(Global): Report Count, data= [ 0x01 ] 1 > Item(Global): Report Size, data= [ 0x06 ] 6 > Item(Main ): Input, data= [ 0x01 ] 1 > Constant Array Absolute No_Wrap Linear > Preferred_State No_Null_Position Non_Volatile Bitfield > Item(Main ): End Collection, data=none I'm not an expert at HID, but this seems clear enough. The report contains two 1-bit items, representing a Volume Increment and a Volume Decrement button, plus a 6-bit item which has no meaning and is always constant (i.e., padding to bring the total size up to 8 bits). That explains why you only see two buttons in the event listing. If you want, you can trace the actual operation of the device by using usbmon. Instructions are in the kernel source file Documentation/usb/usbmon.txt. 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
