Submitting a batchbuffer which simulates a gpu
hang by doing MI_BATCH_BUFFER_START into itself,
to test hangcheck, started to hard hang the whole box
(IVB). Bisecting lead to this commit:
commit 664b422c2966cd39b8f67e8d53a566ea8c877cd6
Author: Vinit Azad <vinit.azad@intel.com>
Date: Wed Aug 14 13:34:33 2013 -0700
drm/i915: Only unmask required PM interrupts
Experimenting with the mask register showed that
unmasking EI UP will prevent the hard hang in IVB and SNB.
HSW doesn't hang with EI UP masked.
Considering we are just disabling interrupts that aren't even
delivered to driver, this change is more likely to paper over some
weirdness in gpu's internal state machine. But until better
explanation can be found, let's trade little bit of power
for stability on these architectures.
v2: - Unmask EI_EXPIRED directly in I915_WRITE (Vinit)
v3: - Only unmask on SNB and IVB
Cc: Vinit Azad <vinit.azad@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Acked-by: Vinit Azad <vinit.azad@intel.com>
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
a9c1f90c8e