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?
Regards,
Axel
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