This patch allows PC8+ states on Haswell. These states can only be
reached when all the display outputs are disabled, and they allow some
more power savings.
The fact that the graphics device is allowing PC8+ doesn't mean that
the machine will actually enter PC8+: all the other devices also need
to allow PC8+.
For now this option is disabled by default. You need i915.allow_pc8=1
if you want it.
This patch adds a big comment inside i915_drv.h explaining how it
works and how it tracks things. Read it.
v2: (this is not really v2, many previous versions were already sent,
but they had different names)
- Use the new functions to enable/disable GTIMR and GEN6_PMIMR
- Rename almost all variables and functions to names suggested by
Chris
- More WARNs on the IRQ handling code
- Also disable PC8 when there's GPU work to do (thanks to Ben for
the help on this), so apps can run caster
- Enable PC8 on a delayed work function that is delayed for 5
seconds. This makes sure we only enable PC8+ if we're really
idle
- Make sure we're not in PC8+ when suspending
v3: - WARN if IRQs are disabled on __wait_seqno
- Replace some DRM_ERRORs with WARNs
- Fix calls to restore GT and PM interrupts
- Use intel_mark_busy instead of intel_ring_advance to disable PC8
v4: - Use the force_wake, Luke!
v5: - Remove the "IIR is not zero" WARNs
- Move the force_wake chunk to its own patch
- Only restore what's missing from RC6, not everything
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
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
c67a470b1d