From: Christoph Hellwig <hch@infradead.org>
To: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: nouveau@lists.freedesktop.org, Joerg Roedel <joro@8bytes.org>,
dri-devel@lists.freedesktop.org,
Christoph Hellwig <hch@infradead.org>,
iommu@lists.linux-foundation.org,
Thierry Reding <thierry.reding@gmail.com>,
Daniel Vetter <daniel@ffwll.ch>,
linux-tegra@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 5/5] ARM: Unconditionally enable ARM_DMA_USE_IOMMU
Date: Wed, 25 Apr 2018 08:17:45 -0700 [thread overview]
Message-ID: <20180425151745.GA16075@infradead.org> (raw)
In-Reply-To: <20180425102511.GP16141@n2100.armlinux.org.uk>
On Wed, Apr 25, 2018 at 11:25:11AM +0100, Russell King - ARM Linux wrote:
> > config ARM_DMA_USE_IOMMU
> > - bool
> > + def_bool y
> > select ARM_HAS_SG_CHAIN
> > select NEED_SG_DMA_LENGTH
>
> This doesn't work - as has recently been discussed with hch, we can't
> globally enable NEED_SG_DMA_LENGTH on ARM - the ARM architecture
> pre-dates the addition of the DMA length member in the scatterlist,
> and not every machine supports the splitting of the DMA length from
> the non-DMA length member. Hence, this will cause a regression,
> sorry.
Agreed as-is. However supporting it everywhere should not be much work,
I'll take a look at it.
WARNING: multiple messages have this Message-ID (diff)
From: hch@infradead.org (Christoph Hellwig)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 5/5] ARM: Unconditionally enable ARM_DMA_USE_IOMMU
Date: Wed, 25 Apr 2018 08:17:45 -0700 [thread overview]
Message-ID: <20180425151745.GA16075@infradead.org> (raw)
In-Reply-To: <20180425102511.GP16141@n2100.armlinux.org.uk>
On Wed, Apr 25, 2018 at 11:25:11AM +0100, Russell King - ARM Linux wrote:
> > config ARM_DMA_USE_IOMMU
> > - bool
> > + def_bool y
> > select ARM_HAS_SG_CHAIN
> > select NEED_SG_DMA_LENGTH
>
> This doesn't work - as has recently been discussed with hch, we can't
> globally enable NEED_SG_DMA_LENGTH on ARM - the ARM architecture
> pre-dates the addition of the DMA length member in the scatterlist,
> and not every machine supports the splitting of the DMA length from
> the non-DMA length member. Hence, this will cause a regression,
> sorry.
Agreed as-is. However supporting it everywhere should not be much work,
I'll take a look at it.
next prev parent reply other threads:[~2018-04-25 15:17 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-25 10:10 [PATCH v2 1/5] drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping Thierry Reding
2018-04-25 10:10 ` Thierry Reding
[not found] ` <20180425101051.15349-1-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-25 10:10 ` [PATCH v2 2/5] dma-mapping: Introduce dma_iommu_detach_device() API Thierry Reding
2018-04-25 10:10 ` Thierry Reding
[not found] ` <20180425101051.15349-2-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-25 15:19 ` Christoph Hellwig
2018-04-25 15:19 ` Christoph Hellwig
[not found] ` <20180425151934.GC16075-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-26 12:11 ` Thierry Reding
2018-04-26 12:11 ` Thierry Reding
2018-04-30 11:02 ` Thierry Reding
2018-04-30 11:02 ` Thierry Reding
2018-04-30 11:41 ` Robin Murphy
2018-04-30 11:41 ` Robin Murphy
[not found] ` <e549979d-9f53-a329-da1a-ed5139958762-5wv7dgnIgG8@public.gmane.org>
2018-04-30 12:12 ` Thierry Reding
2018-04-30 12:12 ` Thierry Reding
2018-04-30 12:49 ` Robin Murphy
2018-04-30 12:49 ` Robin Murphy
2018-04-25 10:10 ` [PATCH v2 3/5] ARM: dma-mapping: Implement arch_iommu_detach_device() Thierry Reding
2018-04-25 10:10 ` Thierry Reding
[not found] ` <20180425101051.15349-3-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-25 15:20 ` Christoph Hellwig
2018-04-25 15:20 ` Christoph Hellwig
[not found] ` <20180425152049.GD16075-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-26 12:14 ` Thierry Reding
2018-04-26 12:14 ` Thierry Reding
2018-04-25 10:10 ` [PATCH v2 4/5] drm/nouveau: tegra: Use dma_iommu_detach_device() Thierry Reding
2018-04-25 10:10 ` Thierry Reding
2018-04-25 10:10 ` [PATCH v2 5/5] ARM: Unconditionally enable ARM_DMA_USE_IOMMU Thierry Reding
2018-04-25 10:10 ` Thierry Reding
[not found] ` <20180425101051.15349-5-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-25 10:25 ` Russell King - ARM Linux
2018-04-25 10:25 ` Russell King - ARM Linux
2018-04-25 15:17 ` Christoph Hellwig [this message]
2018-04-25 15:17 ` Christoph Hellwig
2018-04-25 15:18 ` [PATCH v2 1/5] drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping Christoph Hellwig
2018-04-25 15:18 ` Christoph Hellwig
[not found] ` <20180425151815.GB16075-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-26 12:09 ` Thierry Reding
2018-04-26 12:09 ` Thierry Reding
2018-04-25 15:28 ` Jordan Crouse
2018-04-25 15:28 ` Jordan Crouse
[not found] ` <20180425152849.GA2447-9PYrDHPZ2Orvke4nUoYGnHL1okKdlPRT@public.gmane.org>
2018-04-26 12:41 ` Thierry Reding
2018-04-26 12:41 ` Thierry Reding
2018-04-26 12:59 ` Mikko Perttunen
2018-04-26 12:59 ` Mikko Perttunen
[not found] ` <fd6e0d90-7614-296b-2927-7b2745e8fbde-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2018-04-26 13:14 ` Thierry Reding
2018-04-26 13:14 ` Thierry Reding
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