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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Dave Airlie <airlied@gmail.com>,
	Jerome Glisse <j.glisse@gmail.com>,
	Oded Gabbay <oded.gabbay@gmail.com>,
	dri-devel <dri-devel@lists.freedesktop.org>
Subject: Re: ongoing writecombine on ppc
Date: Fri, 02 Oct 2015 14:45:16 +1000	[thread overview]
Message-ID: <1443761116.2828.64.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAPM=9twpPBLBb6j1ee5_DDv5UqfTzCJh-63CHyDxRU4Xd0ny4g@mail.gmail.com>

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.

_wc is only suitable for MMIO.

Cheers,
Ben.


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  reply	other threads:[~2015-10-02  5:20 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-02  4:42 ongoing writecombine on ppc Dave Airlie
2015-10-02  4:45 ` Benjamin Herrenschmidt [this message]
2015-10-02  4:47   ` Benjamin Herrenschmidt
2015-10-02  4:50     ` Benjamin Herrenschmidt
2015-10-02  4:53   ` Dave Airlie
2015-10-02  4:56     ` Benjamin Herrenschmidt
2016-01-21 15:24       ` Oded Gabbay
2016-01-21 15:39         ` Oded Gabbay
2016-01-21 17:10           ` Alex Deucher
2016-01-22  2:32             ` Michel Dänzer
2016-01-28 14:30               ` Oded Gabbay

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