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

[Keith Packard]

On Thu, 15 Sep 2011 01:27:17 +0200, Samuel Thibault <samuel.thibault at ens-lyon.org> wrote:
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> 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.

-- 
keith.packard at intel.com
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