[mythtv-users] IMON LCD backlight

Ken Johnson kennethjohnson6 at gmail.com
Thu Dec 10 05:04:39 UTC 2009

On Wed, Dec 9, 2009 at 11:01 PM, Jarod Wilson <jarod at wilsonet.com> wrote:

>>> >> > For some reason, this currently seems to be broken, and nobody has come up with a
>>> >> >fix yet. The lcdproc daemon can be configured to turn the display off, and it does turn it
>>> >> >off for a bit during shutdown, but the display lights back up as soon as the box finishes
>>> >> > powering off... So far as I know, we send the exact same display off packet sequence
>>> >> >as windows does, so I can't really explain it. My best guess is that maybe the imon driver
>>> >> >needs to be unloaded cleanly (modprobe -r), sending those display off commands in its
>>> >> >module_exit() routine, and then maybe it'll stay off, but its just a WAG. Not high on my
>>> >> >priority list to poke at it though, but I'd welcome any assistance in determining root cause
>>> >> >and a fix.
>> >>     
> > It's been a few years since I did my initial experiments with the LCD,
> > so I hope my memory is correct.
> >
> > As I recall, you are correct that we do send the same data as windows
> > does. When I was testing, I did both monitoring from the windows side
> > using usb snoopy, and I installed windows in a virtualbox instance
> > running under linux and monitored what usb commands got passed through
> > to the hardware. I couldn't find any sort of command that we aren't
> > passing properly.
> >
> > As far as your modprobe comment, I don't think that's it. I
> > experimented with writing a userspace driver for the device using
> > libusb and I got the same results. It seems unlikely to get the same
> > problem through 2 different interfaces, so I suspect it's something
> > lower level. My WAG has always been something like linux issuing a USB
> > bus reset on poweroff.
> >
> > Anyway, it's annoying, but I learned to live with it....mostly because
> > my machine does suspend-to-ram, and for that the LCD actually stays
> > off.
> >
> > Disclaimer: none of this is very fresh in my memory, so I hope I
> > didn't say something that was inaccurate. Also, I'm not a very
> > experience driver writer, so it's possible I completely screwed up in
> > my testing/debugging methodology. Take that for what it's worth.
> >   
Thanks alot I was hoping that it would be a one time lcd bios set it and
forget it fix but i guess not. thanks anyway

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