ongoing writecombine on ppc

[Oded Gabbay]

+Alex

On Thu, Jan 21, 2016 at 5:24 PM, Oded Gabbay <oded.gabbay at gmail.com> wrote:
> On Fri, Oct 2, 2015 at 7:56 AM, Benjamin Herrenschmidt
> <benh at kernel.crashing.org> wrote:
>> On Fri, 2015-10-02 at 14:53 +1000, Dave Airlie wrote:
>>> On 2 October 2015 at 14:45, Benjamin Herrenschmidt
>>> <benh at kernel.crashing.org> wrote:
>>> > On Fri, 2015-10-02 at 14:42 +1000, Dave Airlie wrote:
>>> > > I don't think we resolved this the last time we talked about it,
>>> > >
>>> > > but radeon writecombine maps fail hard on ppc, I think all the
>>> > > fixes
>>> > > either did something bad to AGP systems or weren't liked.
>>> > >
>>> > > My patch attached just fixes radeon, which is where I'm still
>>> > > seeing
>>> > > the issue.
>>> >
>>> > Yes, you MUST NOT set the flags of system memory to anything other
>>> > than
>>> > fully cachable on any cache coherent powerpc machine. This should
>>> > be
>>> > bolted into the DRM core imho.
>>> >
>>>
>>> Except you guys screwed up and allowed AGP to exist on Power, and
>>> that requires it.
>>
>> Well, Apple did :-) Yes, AGP should never have existed in the first
>> place, I think that's a given :)
>>
>>> So we have to keep the AGP trapdoor in place, and at the moment only
>>> the drivers know if they are AGP, hence why I had to add this in the
>>> driver instead of in the drm core.
>> Cheers,
>> Ben.
>>
>>
>>
> Bumping this and adding my r-b:
> Reviewed-by: Oded Gabbay <oded.gabbay at gmail.com>