On Thu, Nov 26, 2015 at 5:14 PM, Adebisi, YetundeX < [email protected]> wrote:
> Hi, > > > > If the i915 driver is being used then the sysfs option should be > /sys/class/backlight/intel_backlight/brightness. If the intel_backlight > path is not present, then the best thing is to enable debug by adding > drm.debug > =0xe to the kernel command line as Vincent suggested to see what is going > on. > > > > Regards, > > > > Yetunde > > > > *From:* Cheah, Vincent Beng Keat > *Sent:* Thursday, November 26, 2015 6:29 AM > *To:* Chang, Rebecca Swee Fun; Prasant J; Ahmad, Mohd Azril; Adebisi, > YetundeX > > *Cc:* [email protected] > *Subject:* RE: [meta-intel] Intel Atom E3845: Backlight control > > > > +Yetunde. > > > > Hi PJ, > > > > I don’t think we have tried the xrandr option to do backlight but I > believe you should be able to control LVDS backlight simply by accessing > this sysfs à /sys/class/backlight/acpi_video0/brightness (hmm… this > looks pretty much like what you have done below – referring to the PCI > path). Could you please add drm.debug =0xe to enable DRM debug to see what > is going on down there. Also, it would definitely be nice if you can make > your image in run-level-3 to isolate the user-space from the kernel side > when you are testing this. > > > > URL: > > https://wiki.archlinux.org/index.php/Backlight > > > > … Vincent > > > > *From:* Chang, Rebecca Swee Fun > *Sent:* Thursday, November 26, 2015 8:41 AM > *To:* Prasant J <[email protected]>; Cheah, Vincent Beng Keat < > [email protected]>; Ahmad, Mohd Azril < > [email protected]> > *Cc:* [email protected] > *Subject:* RE: [meta-intel] Intel Atom E3845: Backlight control > > > > Hi Vincent/ Azril, > > > > Can you help to provide advice to Pj? > > Thanks. > > > > Regards, > > Rebecca > > > > *From:* [email protected] [ > mailto:[email protected] > <[email protected]>] *On Behalf Of *Prasant J > *Sent:* Wednesday, November 25, 2015 8:46 PM > *To:* [email protected] > *Subject:* [meta-intel] Intel Atom E3845: Backlight control > > > > Hi, > > I'm using Intel Atom E3845 with my custom hardware. I have an LVDS display > and I would like to control the brightness from the linux shell. > > I used the command: > > xrandr --output DP2 --brightness <val> > > This command (I think) changes the gamma factor of the display but the > actual back light intensity is not changed. > > I tried changing the value of: > /sys/devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/brightness > > but still no change in the back light intensity. > > > > Any inputs on how can I control the back light intensity of my LVDS > display? > > > > Regards, Pj > > > Hi Rebecca, Vincent, Yetunde, Thanks for your inputs on my query & sorry for my late response. I got in touch with my hardware vendor on this topic and it turns out that I have not installed certain kernel modules that they provide. Those modules provide back light control. Thanks once again! Regards, Pj
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