brightness control not working
 

I installed trisquel 7.0 lts based on ubuntu in my Dell inspiron 3541 laptop
The laptop is amd apu based. I installed xfce in it.I am not able ti control brightness. Wheb u use the keys in keyboard the brightneas control decreases and increases on screen.But,the brightness is not xhanging.Only the indication in the screen change.actual brightness doesn't change.
How to fix it?

Good luck

Link

If I install nonfree driver from firmware-linux-nonfree,I can control the brightness.But,I can't do so with only libre software.Because in Debian 8,I can control brightness perfectly with non free driver.
But w/o the non free driver the brightness doesn't change.
Is there a way to do so with only libre software?

Yes...run Debian 8. Obviously, the version/distro of Linux you've chosen doesn't have that support, and can't add it without the non-free driver. So either use that driver, or use Debian 8 or another distro.

Thank you.
Seems I have to install the proprietary driver.I downloaded from amd website and installed the same.