Re: issues getting I/O device to work with udev....

[Greg KH <greg@kroah.com>]

On Wed, Aug 30, 2006 at 03:52:39PM +0200, Jan Zwiegers wrote:
> > -----Original Message-----
> > From: linux-hotplug-devel-bounces@lists.sourceforge.net [mailto:linux-
> > hotplug-devel-bounces@lists.sourceforge.net] On Behalf Of Kay Sievers
> > Sent: 27 August 2006 02:18 AM
> > To: jan@eagle.co.za
> > Cc: 'John Thomas'; linux-hotplug-devel@lists.sourceforge.net; 'Ray
> > Schumacher'; md@Linux.IT
> > Subject: RE: issues getting I/O device to work with udev....
> > 
> > On Fri, 2006-08-25 at 21:22 +0200, Jan Zwiegers wrote:
> > > > > > Oh, that all sounds very much like you don't use the right driver
> > core
> > > > > > functions and you create the "dev" file yourself in sysfs. You
> > must use
> > > > > > the right functions in the kernel and pass the correct dev_t to
> > the
> > > > > > device registration. That will automatically create the "dev" file
> > and
> > > > > > add the needed data to the uevent environment, to let udev create
> > the
> > > > > > node.
> > > > > >
> > > > > > But again, to verify this, we need the output of "udevmonitor --
> > env",
> > > > > > while you plug in a device or re-trigger the event by writing
> > "add" to
> > > > > > the "uevent" file in the sysfs device directory.
> > > > >
> > > > >
> > > > > I just create a simple device class by making use of:
> > > > >
> > > > > 'class_device_register' &
> > > > > 'class_device_createfile'
> > > > > to create /sys/class/edredaq/device0 &
> > > > > /sys/class/edredaq/device0/edredaq_nodename
> > > >
> > > > See how class_device_create() works and fills in dev_t, you need to
> > > > convert to that function or do the same with the dev_t value. You also
> > > > need to set the 'device' pointer like that function does, to make
> > > > userspace happy.
> > 
> > > Do you say that I need to look at how I implemented the
> > > class_device_create_file? Mine seems the same as others. Do you think
> > this
> > > is the cause of my problem?
> > 
> > I'm just guessing, but I expect you create the file with the name "dev"
> > which contains the major/minor number yourself in your driver. If that's
> > the case, you shouldn't do that and just set the dev_t value in the
> > device structure before registering the device, that will instruct the
> > driver core to create that file, along with environment variables needed
> > for udev to create a node.
> > 
> > The best way to do this, would probably be to use the
> > class_device_create() function in /linux/drivers/base/class.c, which
> > expects all the needed values as parameters.
> [Jan Zwiegers] 
> Hi Kay & Greg
> 
> Sorry for taking so long to get back to you. 
> 
> The source code is downloadable at
> http://www.eagle.co.za/download/download/edre_linux_drivers_2_0_8.tar.gz
> 
> If you can maybe have a quick look at the class driver. The code is very
> short, so you should be able to quickly understand what is wrong.

Just like Kay guessed, you are not using the proper function call.
Please use the class_device_create() call instead of rolling your own.
That will fix your problem.

And why aren't these drivers in the main kernel tree?  That would make
this a whole lot easier, and save you a lot of time on maintenance.

As it is, I get a whole lot of warnings and errors when trying to build
this code against the latest kernel version :(

If you want, I can help you out in getting this into the kernel tree.
Overall the code looks pretty sane, only a few small cleanups would be
needed (becides the warning fixes...)

thanks,

greg k-h

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