[PATCH] drm/radeon: Disable writeback by default on ppc

[Benjamin Herrenschmidt]

On Wed, 2013-12-04 at 19:05 -0500, Alex Deucher wrote:

> > Setting CP_RB_CNTL.BUF_SWAP causes the CP to use the selected byte
> > swapping for just about everything accessed by the CP (rptr writeback,
> > indirect buffers, etc.).  Looks like the DMA ring supports and enables
> > rptr writeback as well (DMA_RB_CNTL.DMA_RPTR_WRITEBACK_SWAP_ENABLE) so
> > I think we can drop the swapping of the rptr writeback.
> >
> 
> Obvious patch attached.

This works all the way back to r300 ?

Cheers,
Ben.