In the pre-gem days with non-existing hangcheck and gpu reset code,
this timeout of 3 seconds was pretty important to avoid stuck
processes.
But now we have the hangcheck code in gem that goes to great length
to ensure that the gpu is really dead before declaring it wedged.
So there's no need for this timeout anymore. Actually it's even harmful
because we can bail out too early (e.g. with xscreensaver slip)
when running giant batchbuffers. And our code isn't robust enough
to properly unroll any state-changes, we pretty much rely on the gpu
reset code cleaning up the mess (like cache tracking, fencing state,
active list/request tracking, ...).
With this change intel_begin_ring can only fail when the gpu is
wedged, and it will return -EAGAIN (like wait_request in case the
gpu reset is still outstanding).
v2: Chris Wilson noted that on resume timers aren't running and hence
we won't ever get kicked out of this loop by the hangcheck code. Use
an insanely large timeout instead for the HAS_GEM case to prevent
resume bugs from totally hanging the machine.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
************************************************************
* 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
e6bfaf8542