Xorg tearing fix on Intel HD Graphics 4000

[Roel Janssen <roel@gnu.org>]

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Dear Guix,

For a long time now, I have a tearing issue on GuixSD (parts of the
screen do not get updated while others do, resulting in dissapearing
text in Emacs).

With the following patch to the Xorg configuration file, I have a
tear-free GuixSD experience.  I wonder if this is upstreameable in some
way.  This patch is probably too broad in effect.  Can I change it so
that only the graphics card I have will be affected by this patch?

Kind regards,
Roel Janssen


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From 25b431d23071b325b50c584977fcd6c1f9d790af Mon Sep 17 00:00:00 2001
From: Roel Janssen <roel@gnu.org>
Date: Wed, 21 Jun 2017 09:44:46 +0200
Subject: [PATCH] gnu: services: xorg: Fix tearing issue.

* gnu/services/xorg.scm (xorg-configuration-file): Fix tearing issue.
---
 gnu/services/xorg.scm | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/gnu/services/xorg.scm b/gnu/services/xorg.scm
index 5bae8c18e..97f92ab53 100644
--- a/gnu/services/xorg.scm
+++ b/gnu/services/xorg.scm
@@ -133,6 +133,13 @@ EndSection
 Section \"ServerFlags\"
   Option \"AllowMouseOpenFail\" \"on\"
 EndSection
+
+Section \"Device\"
+  Identifier  \"Intel Graphics\"
+  Driver      \"intel\"
+  Option      \"AccelMethod\" \"uxa\" #sna
+  Option      \"DRI\" \"2\"
+EndSection
 "
   (string-join (map device-section drivers) "\n") "\n"
   (string-join (map (cut screen-section <> resolutions)
-- 
2.13.1