67c72a1225
This regression has been introduced in commit 9f11a9e4e50006b615ba94722dfc33ced89664cf Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Thu Jun 13 00:54:58 2013 +0200 drm/i915: set up PIPECONF explicitly for i9xx/vlv platforms Ville brough up the idea that this is just the pipe A quirk gone wrong. Note that after resume the bios might or might not have enabled pipe A already. We have a bit of magic to make sure that on resume we set up a decent mode for pipe A, but I fear if I just smash pipe A to always on we'd enable it in a bogus state and hang the hw. Hence the readback. v2: Clarify the logic a bit as suggested by Chris. Also amend the commit message to clarify why we don't unconditionally enable the pipe. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=66462 References: https://lkml.org/lkml/2013/8/26/238 Cc: Meelis Roos <mroos@ut.ee> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> [danvet: Use |= instead of = as suggested by Chris.] Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************ * For the very latest on DRI development, please see: * * http://dri.freedesktop.org/ * ************************************************************ 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