d52fea5bed
On ILK when we disable a particular watermark level, we must
maintain the actual watermark values for that level for some time
(until the next vblank possibly). Otherwise we risk underruns.
In order to achieve that result we must merge the LP1+ watermarks a
bit differently since we must also merge levels that are to be
disabled. We must also make sure we don't overflow the fields in the
watermark registers in case the calculated watermarks come out too
big to fit.
As early as possbile we mark all computed watermark levels as
disabled if they would exceed the register maximums. We make sure
to leave the actual watermarks for such levels zeroed out. Then during
merging, we take the maxium values for every level, regardless if
they're disabled or not. That may seem a bit pointless since at the
moment all the watermark levels we merge should have their values
zeroed if the level is already disabled. However soon we will be
dealing with intermediate watermarks that, in addition to the new
watermark values, also contain the previous watermark values, and so
levels that are disabled may no longer be zeroed out.
v2: Split the patch in two (Paulo)
Use if() instead of & when merging ->enable (Paulo)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Fix commit message as noted by Paulo.]
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