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Ocypheum

Member

Registered: 2015-09-26

Posts: 58

[Solved] i915 vs. xf86-video-intel (plus backlight woes)

I was having problems with xbacklight, specifically the "No outputs have backlight property" error, which led me to this post. That user was able to solve the problem by installing the Intel xf86 drivers. Even though I've had no other display driver problems using the i915 kernel module, I decided to give it a whirl.

It didn't solve the problem for me, but now I'm wondering if I need to also have xf86-video-intel? Or should I use it instead of the kernel module? Is one better than the other? I understand from the wiki that the xf86 driver provides 2D and 3D acceleration - doesn't the i915 driver do that as well?

lspci -k says I'm still using i915 - do I need to blacklist i915 in order to use intel? Will this even fix the backlight problem, or is that unrelated?

Last edited by Ocypheum (2015-11-08 19:49:24)

Scimmia

Fellow

Registered: 2012-09-01

Posts: 11,598

Re: [Solved] i915 vs. xf86-video-intel (plus backlight woes)

They're two different things. xf86-video-intel is the DDX (device dependent X), i915 is the driver it uses.

If you don't have xf86-video-intel installed, you're probably using the vesa or framebuffer DDX.

Last edited by Scimmia (2015-11-08 04:48:07)

Ocypheum

Member

Registered: 2015-09-26

Posts: 58

Re: [Solved] i915 vs. xf86-video-intel (plus backlight woes)

Ahh so i915 is the main video driver both in and out of X, whereas xf86-video-intel is the driver used specifically in X.

I guess the question then is what's the advantage of the xf86 driver over vesa or framebuffer? And how does one figure out which one is in use?

Edit: by the way, I figured out my backlight problem by making changes to xorg.conf as described here.

Last edited by Ocypheum (2015-11-08 18:44:50)

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,804

Re: [Solved] i915 vs. xf86-video-intel (plus backlight woes)

Vesa and framebuffer do not use any of the advanced functions of your GPU.  All rendering will occur in software.
Read the Xorg.0.log and you will see which drivers it looked at and which one it selected.

You might also look through the output of xdpyinfo and glxinfo, but they don't directly tell you what driver is in use.

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