From: Joerg Roedel <joro@8bytes.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jonathan Marek <jonathan@marek.ca>,
David Airlie <airlied@linux.ie>,
freedreno@lists.freedesktop.org,
open list <linux-kernel@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
iommu@lists.linux-foundation.org, Daniel Vetter <daniel@ffwll.ch>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>, Sean Paul <sean@poorly.run>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 8 Oct 2020 10:27:57 +0200 [thread overview]
Message-ID: <20201008082757.GB3107@8bytes.org> (raw)
In-Reply-To: <20201006072306.GA12834@infradead.org>
On Tue, Oct 06, 2020 at 08:23:06AM +0100, Christoph Hellwig wrote:
> If people want to use the "raw" IOMMU API with not cache coherent
> devices we'll need a cache maintainance API that goes along with it.
> It could either be formally part of the IOMMU API or be separate.
The IOMMU-API does not care about the caching effects of DMA, is manages
IO address spaces for devices. I also don't know how this would be going
to be implemented, the IOMMU-API does not have the concept of handles
for mapped ranges and does not care about CPU virtual addresses (which
are needed for cache flushes) of the memory it maps into IO page-tables.
So I think a cache management API should be separate from the IOMMU-API.
Regards,
Joerg
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prev parent reply other threads:[~2020-10-08 8:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201001002709.21361-1-jonathan@marek.ca>
[not found] ` <20201001002709.21361-3-jonathan@marek.ca>
[not found] ` <20201002075321.GA7547@infradead.org>
[not found] ` <b22fb797-67b0-a912-1d23-2b47c9a9e674@marek.ca>
[not found] ` <20201005082914.GA31702@infradead.org>
[not found] ` <3e0b91be-e4a4-4ea5-7d58-6e71b8d51932@marek.ca>
2020-10-06 7:23 ` [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance Christoph Hellwig
2020-10-06 13:19 ` Jonathan Marek
2020-10-07 6:25 ` Christoph Hellwig
2020-10-13 13:42 ` Robin Murphy
2020-10-13 16:11 ` Rob Clark
2020-10-15 6:55 ` Christoph Hellwig
2020-10-15 15:33 ` Daniel Vetter
2020-10-15 15:43 ` Christoph Hellwig
2020-10-23 6:48 ` Christoph Hellwig
2020-10-08 8:27 ` Joerg Roedel [this message]
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