Better error code from ftdi_write_data()

["rick.walker@xxxxxxxxxxx" <rick.walker@xxxxxxxxxxx>]

Hi all,

 

I'm using libftdi to control a mass spectrometer and am getting hangups every few days.  The symptom is that ftdi_write_data returns -1.  Sometimes I can clear the fault and continue by calling  ftdi_usb_purge_buffers(&ftdic), but I still have a residual number of cases that simply lock the system.

 

I wonder if it would make sense to change the logic slightly in ftdi_write_data:

 

int ftdi_write_data(struct ftdi_context *ftdi, const unsigned char *buf, int size)

{

    ...

    if(libusb_bulk_transfer(ftdi->usb_dev, ftdi->in_ep, (unsigned char *)buf+offset, write_size, &actual_length, ftdi->usb_write_timeout) < 0)

        ftdi_error_return(-1, "usb bulk write failed");

    ...

}

 

It seems like saving the return value from libusb_bulk_transfer and returning that value rather than -1 would make the error culprit more visible.  As it is, the -1 gives no information about what caused libusb_bulk_transfer() to fail.

 

Please let me know if you have any other suggestions for how to recover from a ftdi_write_data error.  I suppose, I could close the context and start over, but maybe there are better approaches.  The target application should run for up to a year reliably without rebooting.

 

Kind regards,

--

Rick Walker

 

 

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