Files
linux/drivers/gpu/drm
Chris Wilson b0b544cd37 drm/i915: Use PM QoS to prevent C-State starvation of gen3 GPU
945 class hardware has an interesting quirk in which the vblank
interrupt is not raised if the CPU is in a low power state. (We also
suspect that the memory bus is clocked to the CPU/c-state and not the
GPU so there are secondary starvation issues.) In order to prevent the
most obvious issue of the low of the vblank interrupt (stuttering
compositing that only updates when the mouse is moving) is to install a
PM QoS request to prevent low c-states whilst the GPU is active.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
2011-01-19 12:38:26 +00:00
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************************************************************
* 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