On Fri, 30 Aug 2013, Kasi Viswanathan wrote: > Hi, > > > I have a custom device, which is usb-hid. But, when i plug it in the > system, > > it is not recognized as a usb-hid device. I have put prints on the > > usbhid_probe() function, to confirm that, but there is no prints in the > > dmesg, which confirms that this is not recognized as a usb-hid device. > > This means that the device's descriptors are bad. What does "lsusb -v" > show? > > Kasi : lsusb -v shows the following info. > /dev/bus/usb/001/008: > Device Descriptor > bcdUSB: 0110 > bDeviceClass: ff 0xff means the device class is vendor-specific. Hence there is no way for the system to tell whether it is or isn't HID. If this value were set to 0 instead, then the system would look at the interface descriptor's bInterfaceClass value, which does indicate that the interface is HID. > bDeviceSubClass: 00 > bDeviceProtocol: 00 > bMaxPacketSize0: 08 > idVendor: 0451 > idProduct: 2f90 > bcdDevice: 1111 > iManufacturer: 00 > iProduct: 00 > iSerialNumber: 00 > bNumConfiguration: 01 > > Config Descriptor > wTotalLength: 0029 > bNumInterfaces: 01 > bConfigurationValue: 01 > iConfiguration: 00 > bmAttributes: 80 > bMaxPower: 100 mA > > Interface Descriptor > bInterfaceNumber: 00 > bAlternateSetting: 00 > bNumEndpoints: 02 > bInterfaceClass: 03 0x03 is USB_CLASS_HID. > > Is there any simple code, which can list all the usb-hid devices that are > > connected to the pc? > > How will that help? > > Kasi : If i have a simple code, then i can once for all determine, if the > HID descriptor provided by the device is valid or not. > > Kindly let me know your view on the same. Listing all the USB HID devices on a PC will not tell you whether the descriptor is valid. The only way to do that is to validate the descriptor. 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
