Cannot connect device to my program on Linux, but it works on Windows

[luxdragon]

Greetings,

I'm using HIDAPI to write a cross-platform library for the FT260 USB-to-I2C bridge and have a problem. The code is available on Codeberg: https://codeberg.org/Zamenhof/FreeFT260

but basically, while the code compiles successfully on both Windows and Linux:

#define VID 0x0403 // Set the VID and PID of your bridge here
#define PID 0x6030


int main(void) {
    unsigned char i2c_hdc2010_addr = 0x40; // Set your address here
    unsigned char eeprom_addr = 0x54; // The EEPROM address
	wchar_t wstr[MAX_STR];

    if (hid_init()) {
        // We initialise the Hidapi backend
        fprintf(stderr, "Failed to initialise the hidapi-Library\n");
        return -1;
    }

    hid_device* device = hid_open(VID, PID, NULL);
    if (!device) {
        fprintf(stderr, "Device not openable: %ls\n", hid_error(NULL));
        hid_exit();
        return -1;
    }

It always returns Device not openable: No HID devices with requested VID/PID found in the system. on Linux even though when I use lsusb the device is found and the VID and PID are correct. I ran the program both with sudo and without and it didn't make a change - according to lsusb my device is the only one with the VID/PID-combo.

How come and how can I fix this issue?

[mcuee]

What is the driver bound to the device? Is it hidraw or some other driver? hidapi under Linux only supports hidraw or libusb. You can print the output of lsusb -t to check the driver binding.

Can you try to detach the kernel hid driver to see if you can use hidapi libusb backend with your device?

[luxdragon]

Heya thank you for your super fast response! Running lsusb gives the following output:

luxdragon@luxdragon:~/Documents/FreeFT260$ lsusb
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 006: ID 0403:6030 Future Technology Devices International, Ltd FT260

and using lsusb -t gives:

luxdragon@luxdragon:~/Documents/FreeFT260$ lsusb -t
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    |__ Port 2: Dev 6, If 0, Class=Human Interface Device, Driver=, 12M
    |__ Port 2: Dev 6, If 1, Class=Human Interface Device, Driver=usbhid, 12M

I tried detatching the module by running:

#include <libusb-1.0/libusb.h>
#include <stdio.h>

int main() {
    libusb_device_handle *handle;
    libusb_context *ctx = NULL;
    int r;

    r = libusb_init(&ctx);
    if (r < 0) {
        fprintf(stderr, "Failed to initialize libusb\n");
        return -1;
    }

    handle = libusb_open_device_with_vid_pid(ctx, 0x0403, 0x6030);
    if (!handle) {
        fprintf(stderr, "Cannot open device\n");
        libusb_exit(ctx);
        return -1;
    }

    if (libusb_kernel_driver_active(handle, 0)) {
        printf("Kernel driver active, detaching it...\n");
        r = libusb_detach_kernel_driver(handle, 0);
        if (r < 0) {
            fprintf(stderr, "Error detaching kernel driver: %s\n", libusb_strerror(r));
            libusb_close(handle);
            libusb_exit(ctx);
            return -1;
        }
    }

    printf("Kernel driver detached\n");
    libusb_close(handle);
    libusb_exit(ctx);
    return 0;
}

But it didn't fix anything

[Youw]

libusb_kernel_driver_active(handle, 0)

You've checked the interface 0 of the device, but it is clear from lsusb -t that If 0 doesn't have any kernel driver active.

---

Try using hid_enumerate and see what devices do you have in your system at all.

Also, you may check manually if your device is present in the system at all, by: ls -l /sys/class/hidraw/ and checking each hidraw device in the system, e.g. by cat /sys/class/hidraw/hidraw0/device/uevent

[luxdragon]

Running hid_enumerate doesn't work, because the command can't be found, should I run the hid_enumerate from the repository.

Running ls -l /sys/class/hidraw/ gives:

lrwxrwxrwx 1 root root 0 Nov 28 07:34 hidraw0 -> ../../devices/platform/AMDI0010:01/i2c-0/i2c-ELAN1200:00/0018:04F3:30BA.0001/hidraw/hidraw0
lrwxrwxrwx 1 root root 0 Nov 28 07:34 hidraw1 -> ../../devices/pci0000:00/0000:00:08.1/0000:05:00.3/usb1/1-2/1-2:1.0/0003:046D:C534.0002/hidraw/hidraw1
lrwxrwxrwx 1 root root 0 Nov 28 07:34 hidraw2 -> ../../devices/pci0000:00/0000:00:08.1/0000:05:00.3/usb1/1-2/1-2:1.1/0003:046D:C534.0003/hidraw/hidraw2
lrwxrwxrwx 1 root root 0 Nov 28 07:34 hidraw3 -> ../../devices/pci0000:00/0000:00:08.1/0000:05:00.3/usb1/1-2/1-2:1.1/0003:046D:C534.0003/0003:046D:4054.0004/hidraw/hidraw3

And as for the last command:

DRIVER=hid-multitouch
HID_ID=0018:000004F3:000030BA
HID_NAME=ELAN1200:00 04F3:30BA
HID_PHYS=i2c-ELAN1200:00
HID_UNIQ=
MODALIAS=hid:b0018g0004v000004F3p000030BA```