ongoing writecombine on ppc

[Alex Deucher]

On Thu, Jan 21, 2016 at 10:39 AM, Oded Gabbay <oded.gabbay at gmail.com> wrote:
> +Alex

No objections from me.  Care to respin with amdgpu support and signed
off?  Would probably also be nice to split the core drm change from
the driver specific ones.

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>