Date: Wed, 4 Jan 2006 14:31:57 -0800
From: Andrew Morton <akpm@osdl.org>
To: "Jason Dravet" <dravet@hotmail.com>
Cc: greg@kroah.com, linux-kernel@vger.kernel.org,
       linux-parport@lists.infradead.org, device@lanana.org
Subject: Re: [RFC]: add sysfs support to parport_pc, v3
Message-Id: <20060104143157.357f9830.akpm@osdl.org>
In-Reply-To: <BAY103-F400667AF1AF50590C4990CDF2F0@phx.gbl>
References: <20060104010841.GA19541@kroah.com>
	<BAY103-F400667AF1AF50590C4990CDF2F0@phx.gbl>
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"Jason Dravet" <dravet@hotmail.com> wrote:
>
> >From: Greg KH <greg@kroah.com>
> > > +++ /usr/src/linux-2.6.14/drivers/parport/parport_pc.c	2006-01-01
> > > 11:29:05.000000000 -0600
> >
> >Line wrapped so it can't be applied :(
> >
> > > + * Added sysfs and udev - Jason Dravet <dravet@hotmail.com>
> > >  */
> >
> >Doesn't belong here, this goes in the change log.
> My mistake.
> 
> > > +#include <linux/sysfs.h>
> >
> >Your email client also ate the leading spaces :(
> My email client is hotmail.  I have come to realize how much hotmail sucks 
> for email.  It eats the leading spaces, converts tabs to spaces, and line 
> wraps.  I will work on getting a new mail account.
> 
> > > +	class_device_create(parallel_class, NULL, MKDEV(6, countports),
> > > NULL, "lp%i", countports);
> > > +	class_device_create(parallel_class, NULL, MKDEV(99, countports),
> > > NULL, "parport%i", countports);
> > > +	countports++;
> >
> >What does the 6 and 99 come from?  Aren't these #defined in a header file 
> >somewhere?
> Good question.  The answer is I have no idea.  I booted Fedora Core and I 
> did a ls -l /dev and wrote down the specs for lp0 and parport0.  lp0 looked 
> like crw-rw----  root   lp   6,  0  date  lp0 so that is what I used.  After 
> reading Linux Device Drivers I found out that 6 is the major number and 0 is 
> the minor number.  The goal was to make sure that the nodes generated by my 
> patch were the same as the nodes generated before my patch so I used those 
> numbers.  Should I have used different major numbers?
> 

6 is OK - it's LP_MAJOR.

However 99 is JSFD_MAJOR, used by drivers/sbus/char/jsflash.c.  And yet my
/dev/parport0 is also 99:0 (RH 7.3 and RH FC1).  I've no idea how that came
about??

bix:/home/akpm> grep parport /etc/makedev.d/*
/etc/makedev.d/generic:a generic parport
/etc/makedev.d/linux-2.4.x:c $PRINTER              99   0  1   8 parport%d
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