Some BIOS just leak the forcewak bits, which we clean up.
Unfortunately this has been broken in
commit 521198a2e7
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date: Fri Aug 23 16:52:30 2013 +0300
drm/i915: sanitize forcewake registers on reset
To make this work both for resets and for BIOS takeover just add the
forcewake clearing call back to intel_uncore_early_sanitize.
We need to clear the forcewake in early sanitize so that the forcewak
dance in intel_uncore_init (to figure out whether we have mt or legacy
forcewake on ivb) works. That cleanup fits in nicely with the general
topic of early_sanitize to prepare for the very first mmio ops.
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Jörg Otte <jrg.otte@gmail.com>
Cc: Jörg Otte <jrg.otte@gmail.com>
References: https://lkml.org/lkml/2013/11/16/40
Cc: stable@vger.kernel.org (for 3.12 only)
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
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
ef46e0d247