From: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
To: "joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org"
<joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: Stuart Yoder <stuart.yoder-3arQi8VN3Tc@public.gmane.org>,
"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
Varun Sethi <V.Sethi-3arQi8VN3Tc@public.gmane.org>,
Peter Newton <peter.newton-3arQi8VN3Tc@public.gmane.org>,
Bharat Bhushan <bharat.bhushan-3arQi8VN3Tc@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: RFC: extend IOMMU attributes
Date: Thu, 25 Feb 2016 15:00:54 +0000 [thread overview]
Message-ID: <20160225150053.GA15330@arm.com> (raw)
In-Reply-To: <20160225143855.GD16675-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
On Thu, Feb 25, 2016 at 03:38:55PM +0100, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org wrote:
> On Thu, Feb 18, 2016 at 04:16:26PM +0000, Stuart Yoder wrote:
> > #define IOMMU_READ (1 << 0)
> > #define IOMMU_WRITE (1 << 1)
> > -#define IOMMU_CACHE (1 << 2) /* DMA cache coherency */
> > +#define IOMMU_CACHE_COHERENT (1 << 2) /* cacheable and coherent */
> > #define IOMMU_NOEXEC (1 << 3)
> > #define IOMMU_MMIO (1 << 4) /* e.g. things like MSI doorbells */
> > +#define IOMMU_CACHEABLE (1 << 5) /* cacheable, not coherent */
> > +#define IOMMU_CACHE_ALLOCATE (1 << 6) /* hint to allocate in the cache */
>
> Hmm, this might be a valid use-case to introduce the
> map_attr()/unmap_attr() calls to the IOMMU-API. I have been resistant to
> these functions until now because the proposed use-cases were not
> convincing, but for hardware-specific map-attributes like this one it
> could make sense.
So this particular use-case is completely insane, but something like
read/write allocation hints could make sense for arm-smmu systems.
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: RFC: extend IOMMU attributes
Date: Thu, 25 Feb 2016 15:00:54 +0000 [thread overview]
Message-ID: <20160225150053.GA15330@arm.com> (raw)
In-Reply-To: <20160225143855.GD16675@8bytes.org>
On Thu, Feb 25, 2016 at 03:38:55PM +0100, joro at 8bytes.org wrote:
> On Thu, Feb 18, 2016 at 04:16:26PM +0000, Stuart Yoder wrote:
> > #define IOMMU_READ (1 << 0)
> > #define IOMMU_WRITE (1 << 1)
> > -#define IOMMU_CACHE (1 << 2) /* DMA cache coherency */
> > +#define IOMMU_CACHE_COHERENT (1 << 2) /* cacheable and coherent */
> > #define IOMMU_NOEXEC (1 << 3)
> > #define IOMMU_MMIO (1 << 4) /* e.g. things like MSI doorbells */
> > +#define IOMMU_CACHEABLE (1 << 5) /* cacheable, not coherent */
> > +#define IOMMU_CACHE_ALLOCATE (1 << 6) /* hint to allocate in the cache */
>
> Hmm, this might be a valid use-case to introduce the
> map_attr()/unmap_attr() calls to the IOMMU-API. I have been resistant to
> these functions until now because the proposed use-cases were not
> convincing, but for hardware-specific map-attributes like this one it
> could make sense.
So this particular use-case is completely insane, but something like
read/write allocation hints could make sense for arm-smmu systems.
Will
next prev parent reply other threads:[~2016-02-25 15:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 16:16 RFC: extend IOMMU attributes Stuart Yoder
2016-02-18 16:16 ` Stuart Yoder
[not found] ` <HE1PR04MB1641F22E38710B68F4ED891F8DAF0-6LN7OEpIatU5tNmRkpaxD89NdZoXdze2vxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
2016-02-18 16:21 ` Will Deacon
2016-02-18 16:21 ` Will Deacon
[not found] ` <20160218162145.GB16883-5wv7dgnIgG8@public.gmane.org>
2016-02-18 19:33 ` Stuart Yoder
2016-02-18 19:33 ` Stuart Yoder
2016-02-25 14:38 ` joro-zLv9SwRftAIdnm+yROfE0A
2016-02-25 14:38 ` joro at 8bytes.org
[not found] ` <20160225143855.GD16675-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2016-02-25 15:00 ` Will Deacon [this message]
2016-02-25 15:00 ` Will Deacon
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