Re: FTDI spontanteous disconnect/reconnect

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Apr 03, 2014 at 07:03:13PM +0200, Sven Lahr wrote:
> Hi there
> 
> I work for a company that produces a system that contains a device with an FTDI 232R chip, as well as a Linux (Debian) computer that the device is attached to.
> We often get reports from our customers that the device is
> disconnected, and then reconnected shortly thereafter. I have searched
> the web, and apparently quite a lot of people experience this when
> they use the Linux driver.

The driver can't disconnect itself from the bus, that sounds like an
electrical issue.

> I wonder if there is any plan to fix this. From what I can tell the
> Linux driver hasn't been updated in 5 years.

Where are you looking?  The in-kernel driver is updated all the time.

> 
> Below I have pasted the relevant part of my kernel log.
> 
> 
> Best regards
> Sven Lähr, Biotage AB, Sweden
> 
> Feb 27 19:45:44 kernel: [  936.368366] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
> Feb 27 19:45:44 kernel: [  936.368379] ftdi_sio 4-2:1.0: device disconnected
> Feb 27 19:45:44 kernel: [  936.608030] usb 4-2: new full-speed USB device number 3 using uhci_hcd
> Feb 27 19:45:44 kernel: [  936.806105] usb 4-2: New USB device found, idVendor=0403, idProduct=6001
> Feb 27 19:45:44 kernel: [  936.806110] usb 4-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> Feb 27 19:45:44 kernel: [  936.806115] usb 4-2: Product: FT232R USB UART
> Feb 27 19:45:44 kernel: [  936.806118] usb 4-2: Manufacturer: FTDI
> Feb 27 19:45:44 kernel: [  936.806121] usb 4-2: SerialNumber: A602WS4T
> Feb 27 19:45:44 kernel: [  936.814150] ftdi_sio 4-2:1.0: FTDI USB Serial Device converter detected
> Feb 27 19:45:44 kernel: [  936.814195] usb 4-2: Detected FT232RL
> Feb 27 19:45:44 kernel: [  936.814198] usb 4-2: Number of endpoints 2
> Feb 27 19:45:44 kernel: [  936.814201] usb 4-2: Endpoint 1 MaxPacketSize 64
> Feb 27 19:45:44 kernel: [  936.814205] usb 4-2: Endpoint 2 MaxPacketSize 64
> Feb 27 19:45:44 kernel: [  936.814208] usb 4-2: Setting MaxPacketSize 64
> Feb 27 19:45:44 kernel: [  936.816223] usb 4-2: FTDI USB Serial Device converter now attached to ttyUSB1

That shows the device disconnecting itself, and then coming back.
Perhaps something is lowering the voltage on the device such that the
host thinks it is gone?

Again, this isn't something that the driver can even do, so I'd start
looking for physical issues first.

thanks,

greg k-h
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