Hi Axel, On Fri, Sep 07, 2012 at 01:24:41PM +0800, Axel Lin wrote: > Hi list, > I have a tablet that shows it is a HID device. > But the report descriptor looks broken. > > Below shows the device information: > > lsusb -v: > > Bus 002 Device 004: ID 04b4:3045 Cypress Semiconductor Corp. > Device Descriptor: > bLength 18 > bDescriptorType 1 > bcdUSB 1.10 > bDeviceClass 0 (Defined at Interface level) > bDeviceSubClass 0 > bDeviceProtocol 0 > bMaxPacketSize0 8 > idVendor 0x04b4 Cypress Semiconductor Corp. > idProduct 0x3045 > bcdDevice 1.00 > iManufacturer 1 Ping-IT > iProduct 2 RS232_USB > iSerial 0 > bNumConfigurations 1 > Configuration Descriptor: > bLength 9 > bDescriptorType 2 > wTotalLength 34 > bNumInterfaces 1 > bConfigurationValue 1 > iConfiguration 3 Bus power > bmAttributes 0xa0 > (Bus Powered) > Remote Wakeup > MaxPower 100mA > Interface Descriptor: > bLength 9 > bDescriptorType 4 > bInterfaceNumber 0 > bAlternateSetting 0 > bNumEndpoints 1 > bInterfaceClass 3 Human Interface Device > bInterfaceSubClass 0 No Subclass > bInterfaceProtocol 0 None > iInterface 4 HID > HID Device Descriptor: > bLength 9 > bDescriptorType 33 > bcdHID 1.10 > bCountryCode 0 Not supported > bNumDescriptors 1 > bDescriptorType 34 Report > wDescriptorLength 26 > Report Descriptors: > ** UNAVAILABLE ** > Endpoint Descriptor: > bLength 7 > bDescriptorType 5 > bEndpointAddress 0x81 EP 1 IN > bmAttributes 3 > Transfer Type Interrupt > Synch Type None > Usage Type Data > wMaxPacketSize 0x0008 1x 8 bytes > bInterval 10 > Device Status: 0x0000 > (Bus Powered) > > And below is the report descriptor ( by usbhid-dump / hidrd-convert ) > > 0x05, 0x0D, /* Usage Page (Digitizer), */ > 0x09, 0x08, /* Usage (3D Digitizer), */ > 0xA1, 0x01, /* Collection (Application), */ > 0x09, 0x01, /* Usage (Digitizer), */ > 0xA1, 0x00, /* Collection (Physical), */ > 0x05, 0x01, /* Usage Page (Desktop), */ > 0x09, 0x3B, /* Usage (Byte Count), */ > 0x15, 0x00, /* Logical Minimum (0), */ > 0x25, 0x7F, /* Logical Maximum (127), */ > 0x75, 0x08, /* Report Size (8), */ > 0x95, 0x07, /* Report Count (7), */ > 0x81, 0x02, /* Input (Variable), */ > 0xC0, /* End Collection, */ > 0xC0 /* End Collection */ > > The report descriptor looks broken to me: > 1. The report descriptor does not have Usage for TOOL_PEN/STYLUS/STYLUS2/PRESSURE, > so evdev doest not recognized it as a tablet. > Actually, the report descriptor does not define any detail of the data. > It only shows a 7 bytes report content. > 2. It does not have Report ID field. > (Does it make sense to have a report descriptor without Report ID field?) > > So in this case, should I implement a HID (special device) driver or > a input driver (in drivers/input/tablet folder) for this device? > I think because the driver would hardly use any of HID infrastructure it would make sense to do it as an input driver. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
