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Zhao Yakui
a8ebba75b3
The BDW GT3 has two independent BSD rings, which can be used to process the video commands. To be simpler, it is transparent to user-space driver/middle. Instead the kernel driver will decide which ring is to dispatch the BSD video command. As every BSD ring is powerful, it is enough to dispatch the BSD video command based on the drm fd. In such case it can play back video stream while encoding another video stream. The coarse ping-pong mechanism is used to determine which BSD ring is used to dispatch the BSD video command. V1->V2: Follow Daniel's comment and use the simple ping-pong mechanism. This is only to add the support of dual BSD rings on BDW GT3 machine. The further optimization will be considered in another patch set. V2->V3: Follow Daniel's comment to use the struct_mutext instead of atomic_t during determining which ring can be used to dispatch Video command. Reviewed-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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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