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From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: robh+dt@kernel.org, frowand.list@gmail.com,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, hch@lst.de,
	m.szyprowski@samsung.com, stefan.wahren@i2se.com,
	afaerber@suse.de, hverkuil@xs4all.nl, johan@kernel.org
Subject: Re: [PATCH 1/2] of: Fix DMA mask generation
Date: Fri, 11 Aug 2017 19:56:41 +0200	[thread overview]
Message-ID: <20170811175641.GA1921@lst.de> (raw)
In-Reply-To: <0819179085df6c41c70e83a2c5c138b95c0386b3.1502468875.git.robin.murphy@arm.com>

On Fri, Aug 11, 2017 at 05:29:56PM +0100, Robin Murphy wrote:
> Historically, DMA masks have suffered some ambiguity between whether
> they represent the range of physical memory a device can access, or the
> address bits a device is capable of driving, particularly since on many
> platforms the two are equivalent. Whilst there are some stragglers left
> (dma_max_pfn(), I'm looking at you...), the majority of DMA code has
> been cleaned up to follow the latter definition, not least since it is
> the only one which makes sense once IOMMUs are involved.

I think it always was supposed to be the latter, but that doesn't mean
that everyone got the message :)

> Either of these patches alone should be sufficient to un-break RPi3,
> and they apply independently, so I'm quite happy for one to go in as a
> fix now and the other to wait for 4.14.

This one is something I'm comfortable feeding to Linus for 4.13
if I get a few ACKs from people familar with the OF code and intended
meaning of the ranges in the device tree.

WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] of: Fix DMA mask generation
Date: Fri, 11 Aug 2017 19:56:41 +0200	[thread overview]
Message-ID: <20170811175641.GA1921@lst.de> (raw)
In-Reply-To: <0819179085df6c41c70e83a2c5c138b95c0386b3.1502468875.git.robin.murphy@arm.com>

On Fri, Aug 11, 2017 at 05:29:56PM +0100, Robin Murphy wrote:
> Historically, DMA masks have suffered some ambiguity between whether
> they represent the range of physical memory a device can access, or the
> address bits a device is capable of driving, particularly since on many
> platforms the two are equivalent. Whilst there are some stragglers left
> (dma_max_pfn(), I'm looking at you...), the majority of DMA code has
> been cleaned up to follow the latter definition, not least since it is
> the only one which makes sense once IOMMUs are involved.

I think it always was supposed to be the latter, but that doesn't mean
that everyone got the message :)

> Either of these patches alone should be sufficient to un-break RPi3,
> and they apply independently, so I'm quite happy for one to go in as a
> fix now and the other to wait for 4.14.

This one is something I'm comfortable feeding to Linus for 4.13
if I get a few ACKs from people familar with the OF code and intended
meaning of the ranges in the device tree.

  parent reply	other threads:[~2017-08-11 17:56 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-11 16:29 [PATCH 1/2] of: Fix DMA mask generation Robin Murphy
2017-08-11 16:29 ` Robin Murphy
2017-08-11 16:29 ` Robin Murphy
2017-08-11 16:29 ` [PATCH 2/2] of: Restrict DMA configuration Robin Murphy
2017-08-11 16:29   ` Robin Murphy
2017-08-11 18:01   ` Christoph Hellwig
2017-08-11 18:01     ` Christoph Hellwig
2017-08-11 18:01     ` Christoph Hellwig
2017-08-14 20:08   ` Rob Herring
2017-08-14 20:08     ` Rob Herring
2017-08-14 20:08     ` Rob Herring
2017-08-15 10:18     ` Robin Murphy
2017-08-15 10:18       ` Robin Murphy
2017-08-15 10:18       ` Robin Murphy
2017-08-15 14:19       ` Rob Herring
2017-08-15 14:19         ` Rob Herring
2017-08-15 14:19         ` Rob Herring
2017-08-25 14:54         ` Christoph Hellwig
2017-08-25 14:54           ` Christoph Hellwig
2017-08-11 17:56 ` Christoph Hellwig [this message]
2017-08-11 17:56   ` [PATCH 1/2] of: Fix DMA mask generation Christoph Hellwig
2017-08-14 21:09 ` Rob Herring
2017-08-14 21:09   ` Rob Herring
2017-08-14 21:09   ` Rob Herring
2017-08-17  8:24   ` Christoph Hellwig
2017-08-17  8:24     ` Christoph Hellwig

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