From: Arnd Bergmann <arnd@arndb.de>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Bill Mills <wmills@ti.com>,
rmk+kernel@armlinux.org.uk, t-kristo@ti.com, ssantosh@kernel.org,
catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, r-woodruff2@ti.com,
devicetree@vger.kernel.org
Subject: Re: [RFC v2 4/4] ARM: keystone: dma-coherent with safe fallback
Date: Mon, 06 Jun 2016 14:37:24 +0200 [thread overview]
Message-ID: <4810162.vDdHVxWF0U@wuerfel> (raw)
In-Reply-To: <20160606114256.GF6831@leverpostej>
On Monday, June 6, 2016 12:42:56 PM CEST Mark Rutland wrote:
> On Mon, Jun 06, 2016 at 11:09:07AM +0200, Arnd Bergmann wrote:
> > On Monday, June 6, 2016 9:56:27 AM CEST Mark Rutland wrote:
> >
> > So far, the assumption has been:
> >
> > - when running a non-LPAE kernel, keystone is not coherent, and we
> > must ignore both the dma-coherent properties in devices and the
> > dma-ranges properties in bus nodes.
>
> I wasn't able to spot if/where that was enforced. Is it possible to boot
> Keystone UP, !LPAE?
With !LPAE, no devices are coherent, so that should work with both
SMP and and UP. Not sure about LPAE with coherent devices on UP,
IIRC we had a bug in that configuration on Armada XP, as the memory
was not marked as sharable at all there, and ended up not being
coherent with DMA masters.
My first guess is that uniprocessor mode on keystone has not been
tested at all (TI's QA seems to test only a very limited number of
configurations), so it may or may not work.
Arnd
next prev parent reply other threads:[~2016-06-06 22:32 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-06 3:20 [RFC v2 0/4] ARM LPAE Outer Shared v2 Bill Mills
2016-06-06 3:20 ` [RFC v2 1/4] ARM: mm: add early page table attribute modification ability Bill Mills
2016-06-06 12:18 ` Russell King - ARM Linux
2016-06-06 12:31 ` William Mills
2016-06-06 3:20 ` [RFC v2 2/4] ARM: mm: Add LPAE support for outer shared Bill Mills
2016-06-06 3:20 ` [RFC v2 3/4] ARM: mm: add inner/outer sharing value command line Bill Mills
2016-06-06 3:20 ` [RFC v2 4/4] ARM: keystone: dma-coherent with safe fallback Bill Mills
2016-06-06 8:56 ` Mark Rutland
2016-06-06 9:09 ` Arnd Bergmann
2016-06-06 11:42 ` Mark Rutland
2016-06-06 12:37 ` Arnd Bergmann [this message]
2016-06-06 12:50 ` William Mills
2016-06-06 16:18 ` Santosh Shilimkar
2016-06-06 11:43 ` Russell King - ARM Linux
2016-06-06 11:59 ` Mark Rutland
2016-06-06 12:19 ` William Mills
2016-06-06 12:32 ` Russell King - ARM Linux
2016-06-06 16:28 ` Santosh Shilimkar
2016-06-07 10:01 ` Mark Rutland
2016-06-07 12:32 ` Russell King - ARM Linux
2016-06-07 12:55 ` Mark Rutland
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