libftdi Archives

Subject: Re: libusb device search problem

From: Robert Hubley <rhubley@xxxxxxxxxxxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Wed, 29 Sep 2010 16:20:17 -0700
Thanks for the feedback. For the record, I am not submitting a bug...but rather a helpful google searchable solution to a legacy problem. As many of us embedded programmers are dealing with 2.4 and early 2.6 kernels on this type of info is golden when you don't have an option to upgrade. Perhaps when I have much much more time I will look into why /dev/bus/usb is not being populated. Nah...I will just go on vacation if I ever get that time. :-)


On 9/29/10 4:16 PM, Xiaofan Chen wrote:
On Thu, Sep 30, 2010 at 6:23 AM, Robert Hubley
<rhubley@xxxxxxxxxxxxxxxxxx>  wrote:
  Heads up.  While tracking down a problem with libftdi not seeing my clearly
attached USB device.  I found a potential problem with the way libusb
searches for USB devices under the linux OS.  It uses a priority search
starting with an environment variable followed by the /dev/bus/usb hierarchy
and then the /proc/bus/usb hierarchy.  On my particular Debian system it
looks like /dev/bus/usb is only partially populated with devices ( perhaps
the ones supported by kernel drivers??? ), while /proc/bus/usb contains a
dynamic list of all the devices.  I solved the problem by reversing the
order of this search ( /proc/bus/usb first ).  Not a problem with libftdi
per se...but I wanted to put this up somewhere in case anyone else was
banging their heads over this.

I guess you are using libftdi-0.1x and libusb-0.1 under Debian.
Just take note libusb-0.1 is not maintained any more and
all the tickers submitted got a "wontfix" solution.

And /proc/bus/usb is not available for most of the modern

And the proper fix is try to figure out why the  /dev/bus/usb is
only partially populated in your particular distro.

libftdi - see for details.
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