a8a8bd547e
Currently, when our driver becomes idle for i915.pc8_timeout (default:
5s) we enable PC8, so we save some power, but not everything we can.
Then, while PC8 is enabled, if we stay idle for more
autosuspend_delay_ms (default: 10s) we'll enter runtime PM and put the
graphics device in D3 state, saving even more power. The two features
are separate things with increasing levels of power savings, but if we
disable PC8 we'll never get into D3.
While from the modularity point of view it would be nice to keep these
features as separate, we have reasons to merge them:
- We are not aware of anybody wanting a "PC8 without D3" environment.
- If we keep both features as separate, we'll have to to test both
PC8 and PC8+D3 code paths. We're already having a major pain to
make QA do automated testing of just one thing, testing both paths
will cost even more.
- Only Haswell+ supports PC8, so if we want to add runtime PM support
to, for example, IVB, we'll have to copy some code from the PC8
feature to runtime PM, so merging both features as a single thing
will make it easier for enabling runtime PM on other platforms.
This patch only does the very basic steps required to have PC8 and
runtime PM merged on a single feature: the next patches will take care
of cleaning up everything.
v2: - Rebase.
v3: - Rebase.
- Fully remove the deprecated i915 params since Daniel doesn't
consider them as part of the ABI.
v4: - Rebase.
- Fix typo in the commit message.
v5: - Rebase, again.
- Add a huge comment explaining the different forcewake usage
(Chris, Daniel).
- Use open-coded forcewake functions (Daniel).
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Imre Deak <imre.deak@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