Hi ... I'm using an ARM Samsung S3C24XX processor with a 3.1.10 kernel.
I'm interested in creating medical equipment using Linux and came onto
an issue today. I've created an application that connects to two FTDI
devices and reads continuous data from a medical sensor. I have a
custom based board ( no external ports ), and my FTDI devices go
directly to the S3C24xx USB pins and my app is configured to read from a
specific product, vendor and device address location. I've been testing
it without problems and today it stopped working. Apparently, when
checking the *dmesg* messages, the kernel disconnected those two USB
devices and assigned them two new addresses ( 5 and 6 ) different from
the original 3 and 4. I always noticed on PC's that this issue was
somehow related to hardware problems and/or disconnection from the USB
port. Also both the /dev/ttyUSB0 and /dev/ttyUSB1 devices on the /dev
directory dissapeared ( for now not a problem since I don't access the
FTDI device this way ). These are the kernel messages:
usb 1-1.3: USB disconnect, device number 3
usb 1-1.4: USB disconnect, device number 4
usb 1-1: reset full speed USB device number 2 using s3c2410-ohci
usb 1-1.3: new full speed USB device number 5 using s3c2410-ohci
usb 1-1.4: new full speed USB device number 6 using s3c2410-ohci
On my board I can't hook up my application again to the new address
since it's the only parameter identifiable by it. Both FTDI Devices
have the same product and vendor numbers:
Bus 001 Device 003: ID 0403:6001
Bus 001 Device 004: ID 0403:6001
The address on which they are on is the only ID I've got. Is there
some way to disable the kernel usb reset policy or assign them a
specific address ?? I'm using *mdev* from userspace but the type of
address assignment with mdev is the one concerning the device's name
under the /dev directory AFAIK ...
Thanks ...
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