linux-kernel - Re: understanding firmware loader for speedtouch (kernel 2.6.21.5)

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Date:	Mon, 09 Jul 2007 17:08:01 +0200
From:	Kay Sievers <kay.sievers@...y.org>
To:	mikie <mikie.pl@...il.com>
Cc:	Indan Zupancic <indan@....nu>,
	Duncan Sands <duncan.sands@...h.u-psud.fr>,
	linux-kernel@...r.kernel.org
Subject: Re: understanding firmware loader for speedtouch (kernel 2.6.21.5)

On Mon, 2007-07-09 at 16:40 +0200, mikie wrote:
> 2007/7/9, Kay Sievers <kay.sievers@...y.org>:
> > On 7/9/07, mikie <mikie.pl@...il.com> wrote:
> > > 2007/7/9, Indan Zupancic <indan@....nu>:
> > > > On Mon, July 9, 2007 10:49, mikie wrote:
> > > > > 2007/7/6, Indan Zupancic <indan@....nu>:
> > > > >> On Fri, July 6, 2007 16:20, Duncan Sands wrote:
> > > > >> > On Friday 6 July 2007 14:54:18 mikie wrote:
> > > > >> >> Hi,
> > > > >> >>
> > > > >> >> I experience some problems with the speedtch.c module, especially in
> > > > >> >> regards to its firmware loader.
> > > > >> >> I am not quite sure if this module is going to load the firmware
> > > > >> >> itself or does it use some external software to do that ?
> > > > >> >
> > > > >> > It loads it itself, using some external software!
> > > > >>
> > > > >> For information, it generates a hotplug event and the kernel calls the
> > > > >> program written at /proc/sys/kernel/hotplug with certain information.
> > > > >> That used to be /sbin/hotplug, became later udev, but today in general
> > > > >> udev reads the uevents generated by the kernel.
> > > > >
> > > > > On my system the /proc/sys/kernel/hotplug points to /sbin/hotplug.
> > > > > I copied your script to /sbin/hotplug and also added simple logging,
> > > > > so I can see whenever the script is being started. It turns out that
> > > > > the script is not started at all by the kernel...
> > > > >
> > > > > I am afraid that the kernel generates uevents only, could this be true?
> > > >
> > > > Not really, it would break backward compatibility, and if it were true,
> > > > they're remove the /proc/sys/kernel/hotplug setting too. As far as I know,
> > > > if it's set, that program will be executed, and if zero is written to it, only
> > > > uevents are generated.
> > > >
> > > > Make sure that the script is executable (chmod +x)
> > >
> > > Yes I have set it to be executable:
> > > root@srv:/sbin# ls -lah hotplug
> > > -rwxr-xr-x    1 root     root          934 Jul  9 09:13 hotplug
> > >
> > > > and has "#!/bin/sh"
> > > > at the top, or else it won't work. If that's already the case, I've no idea.
> > >
> > > root@srv:/sbin# head hotplug
> > > #!/bin/sh
> > > set -e
> > >
> > >
> > > Everything looks OK, but still it does not fire up the script...
> >
> > It should run, if the kernel creates events. Can you run "udevmonitor
> > --env" while loading the driver? That way we can see if events are
> > generated by the kernel (if you don't have it, no need to install
> > udev, just download the udev tarball, type "make" and run
> > "./udevmonitor --env").
> 
> It seems that uevents are generated:
> 
> UEVENT[1183991915.577581] add      /class/firmware/1-2:1.0 (firmware)
> ACTION=add

Using /sbin/hotplug works without any problems here:

$ uname -a
Linux lov 2.6.22-dirty #68 SMP Mon Jul 9 03:43:51 CEST 2007 x86_64 x86_64 x86_64 GNU/Linux

$ cat /proc/sys/kernel/hotplug 
/sbin/hotplug

$ ls -l /sbin/hotplug
-rwxr-xr-x 1 root root 39 2007-07-09 17:02 /sbin/hotplug

$ cat /sbin/hotplug
#!/bin/sh
set | logger -t "hotplug $$"

$ tail -50 /var/log/messages
...
Jul  9 17:04:33 lov hotplug 15589: ACTION=add
Jul  9 17:04:33 lov hotplug 15589: BASH=/bin/sh
Jul  9 17:04:33 lov hotplug 15589: BASH_ARGC=([0]="1")
Jul  9 17:04:33 lov hotplug 15589: BASH_ARGV=([0]="usb_endpoint")
Jul  9 17:04:33 lov hotplug 15589: BASH_LINENO=([0]="0")
Jul  9 17:04:33 lov hotplug 15589: BASH_SOURCE=([0]="/sbin/hotplug")
Jul  9 17:04:33 lov hotplug 15589: MAJOR=254
Jul  9 17:04:33 lov hotplug 15589: MINOR=11
Jul  9 17:04:33 lov hotplug 15589: SUBSYSTEM=usb_endpoint
...

Kay

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