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Daniel Vetter
b6f69c9a7f
This has been tons of fun to figure out with git blame. The first notion of this code block goes back to the original cpu edp enabling for ilk in commit32f9d658aeAuthor: Zhenyu Wang <zhenyuw@linux.intel.com> Date: Fri Jul 24 01:00:32 2009 +0800 drm/i915: Add eDP support on IGDNG mobile chip Two things are notable in this commit wrt to the this edp special case: - The IS_eDP check _only_ fires for DP A, i.e. cpu edp ports. - The cpu edp port is disabled at the top of the dp_link_down function. My theory is that these hacks was added to work around the completely different modeset sequence for cpu edp ports compared to pch edp ports. With the cpu edp confusion on ilk (and snb/ivb) now fixed up, this shouldn't be required any more. The really interesting question is how this special cases survived this long in the code. The first step is declaring the pch port D as eDP if it's used for an internal panel: commitb329530ca7Author: Adam Jackson <ajax@redhat.com> Date: Fri Jul 16 14:46:28 2010 -0400 drm/i915/dp: Correctly report eDP in the core connector type This commit unfortunately failed to notice that not all edp ports are created equal. Then follow a flurry of refactorings, culminating in a patch from Keith Packard which resulted in the current logic (by making it "correct" for all platforms that have edp): commit417e822deeAuthor: Keith Packard <keithp@keithp.com> Date: Tue Nov 1 19:54:11 2011 -0700 drm/i915: Treat PCH eDP like DP in most places None of these cleanups or refactorings supply any reason why we need this code, they've simply carried it on as-is. Hence presume it might be harmful with the current code and rip it out. We do rewrite the link training bits completely anyway when re-training the link. Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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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