[ added linux-usb to CC ] On Thu, 13 Aug 2009, Zeisel, Michael wrote: > We experienced those problems with one of our devices, the Digital > Pocket Memo 3 (DPM), by simply trying to receive button events via the > > Cat /dev/usb/hiddev0 > > Command -> no success. The only difference between this device and older > ones (which work on this kernel version) in the USB descriptor is the > data payload which is 64 byte. > > To narrow down the cause for that behavior we simply took the same > device, put in a FW with a low speed device protocol with a data payload > of 8 byte and plugged it again to the PC. > > Now the button events produced some symbols in the "terminal", which > proves that the device was recognized correctly and works. > > According to the USB 2.0 specification under > > http://www.usb.org/developers/docs/ > > USB 2.0 specification, Chapter 5.7.4: Interrupt Transfer Bus Access Constraints > > A full speed device should support a maximum data payload of 64 bytes > (Table 5-7. Full-speed Interrupt Transaction Limits: max.payload 64 > bytes x max.transfers 19 = max. 1216bytes/frame) > > To us it seems that the current implementation of the HID device support > in LINUX just supports the protocol for low speed devices (Table 5-6. > Low-speed Interrupt Transaction Limits: max.payload 8 bytes x > max.transfers 6 = max. 48bytes/frame) > > On Windows OS and Mac OS all our devices work properly. Could you please compile your kernel with CONFIG_USB_DEBUG and CONFIG_HID_DEBUG enabled, modprobe the 'hid' module with 'debug=2' parameter, and post the dmesg output that appears when you connect the device and press the buttons? > I think it is a good idea, if you would have a Digital Pocket Memo to > experience the described behavior- so to whom I should send that device? Let's see if something obvious pops out from the kernel debugging logs first. Thanks, -- Jiri Kosina SUSE Labs -- 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
