Re: [REGRESSION] i915 KMS dual head broken on DELL latitude E6420 in 3.1-rc*

On Thu, 15 Sep 2011 01:27:17 +0200, Samuel Thibault samuel.thibault@ens-lyon.org wrote: Non-text part: multipart/mixed

Hello,

I'm trying to upgrade from 3.0 to 3.1-rcsomething on a DELL latitude E6420, but dual head is broken. Here is the scenario:

• Turn computer on with VGA1 connected. Both LVDS1 and VGA1 show the text console fine.
• Start X. VGA1 shows X fine, but LVDS1 (1600x900 resolution) shows an odd screen: completely black on the left part (about 1060x900), sort of gray on the right part (about 540x900). Playing with xrandr doesn't help, I can at best make it completely black with --off, and not get it back again with --auto or anything else.

Can you try disabling frame buffer compression?

i915.i915_enable-fbc=0

I'm about to send a patch to disable this by default; I've gotten two people saying that this helps them already.