[Intel-gfx] DDC on Thinkpad x220

[Pavel Machek]

On Tue 2019-10-01 12:39:34, Jani Nikula wrote:
> On Mon, 30 Sep 2019, Pavel Machek <pavel at ucw.cz> wrote:
> > Hi!
> >
> > Thinkpad X220 should be new enough machine to talk DDC to the
> > monitors, right? And my monitor has DDC enable/disable in the menu, so
> > it should support it, too...
> >
> > But I don't have /dev/i2c* and did not figure out how to talk to the
> > monitor. Is the support there in the kernel? What do I need to enable
> > it?
> 
> # modprobe i2c-dev

Thanks!

I enabled I2C_CHARDEV, and installed ddccontrol:

c   ddccontrol                      - program to control monitor

I can read parameters of Dell monitor on VGA:

sudo ddccontrol dev:/dev/i2c-1 -c -d
/usr/share/ddccontrol-db/monitor/DELA013.xml
Control 0x10: +/79/100   [???] -- brightness
Control 0x12: +/63/100   [???] -- contrast

Unfortunately the Fujitsu monitor does not seem to
communicate. Fujitsu is my main monitor :-(.

pavel at duo:~$ sudo ddccontrol dev:/dev/i2c-4 -c -d
ddccontrol version 0.4.2
Copyright 2004-2005 Oleg I. Vdovikin (oleg at cs.msu.su)
Copyright 2004-2006 Nicolas Boichat (nicolas at boichat.ch)
This program comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of this program under the terms of the GNU
General Public License.

Reading EDID and initializing DDC/CI at bus dev:/dev/i2c-4...
ioctl(): No such device or address
ioctl returned -1
ioctl(): No such device or address
ioctl returned -1
ioctl(): No such device or address
ioctl returned -1
I/O warning : failed to load external entity
"/usr/share/ddccontrol-db/monitor/FUS080A.xml"
Document not parsed successfully.
ioctl(): No such device or address
ioctl returned -1

DDC/CI at dev:/dev/i2c-4 is unusable (-1).
If your graphics card need it, please check all the required kernel
modules are loaded (i2c-dev, and your framebuffer driver).

Any further hints?

Thanks and best regards,
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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