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linux/drivers/gpu/drm
Benjamin Herrenschmidt df07d6999e drm/radeon: Writeback endian fixes
The writeback ring pointer and IH ring pointer are read using le32_to_cpu
so we do not want the chip to byteswap them on big-endian.

We still want to byteswap the ring itself and the IBs, so we don't touch
that but we remove setting of the byteswap bits in CP_RB_RPTR_ADDR and
IH_CNTL.

In general, for things like that where we control all the accessors easily,
we are better off doing the swap in SW rather than HW. Paradoxally, it does
keep the code closer to x86 and avoid using poorly tested HW features.

I also changed the use of RADEON_ to R600_ in a couple of cases to be more
consistent with the surrounding code.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Michel Dänzer <michel@daenzer.net>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-07-25 12:14:56 +01:00
..
2011-07-25 12:14:56 +01:00
2011-07-13 08:30:22 +01:00

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