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commitbf2125e2f7upstream. Otherwise the hw will get confused and result in a black screen. This regression has been most likely introduce in commit974b93315bAuthor: Chris Wilson <chris@chris-wilson.co.uk> Date: Sun Sep 5 00:44:20 2010 +0100 drm/i915/tv: Poll for DAC state change That commit replace the first msleep(20) with a busy-loop, but failed to keep the 2nd msleep around. Later on we've replaced all these msleep(20) by proper vblanks. For reference also see the commit in xf86-video-intel: commit 1142be53eb8d2ee8a9b60ace5d49f0ba27332275 Author: Jesse Barnes <jbarnes@hobbes.lan> Date: Mon Jun 9 08:52:59 2008 -0700 Fix TV programming: add vblank wait after TV_CTL writes Fxies FDO bug #14000; we need to wait for vblank after writing TV_CTL or following "DPMS on" calls may not actually enable the output. v2: As suggested by Chris Wilson, add a small comment to ensure that no one accidentally removes this vblank wait again - there really seems to be no sane explanation for why we need it, but it is required. Launchpad: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/763688 Reported-and-Tested-by: Robert Lowery <rglowery@exemail.com.au> Cc: Rodrigo Vivi <rodrigo.vivi@gmail.com> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html