Files
kernel_arpi/drivers/gpu/drm
Rob Clark f7eff60ea0 drm: refcnt drm_framebuffer (v4.1)
This simplifies drm fb lifetime, and if the crtc/plane needs to hold
a ref to the fb when disabling a pipe until the next vblank, this
avoids the need to make disabling an overlay synchronous.  This is a
problem that shows up when userspace is using a drm plane to
implement a hw cursor.. making overlay disable synchronous causes
a performance problem when x11 is rapidly enabling/disabling the
hw cursor.  But not making it synchronous opens up a race condition
for crashing if userspace turns around and immediately deletes the
fb.  Refcnt'ing the fb makes it possible to solve this problem.

v1: original
v2: add drm_framebuffer_remove() which is called in all paths where
    fb->funcs->destroy() was directly called before.  This cleans
    up the CRTCs/planes that the fb was attached to.  You should
    only directly use drm_framebuffer_unreference() if you are also
    using drm_framebuffer_reference() to keep a ref to the fb.
v3: add comment explaining the fb refcount
v4: remove duplicate 'list_del(&fb->filp_head)'

[airlied: v4.1: fix local rejection]

Signed-off-by: Rob Clark <rob@ti.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-10-02 22:15:39 +10:00
..
2012-10-02 22:15:39 +10:00
2012-10-02 22:15:39 +10:00
2012-09-13 11:28:39 +10:00
2012-09-18 12:28:22 +02:00
2012-09-18 12:28:22 +02:00

************************************************************
* 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