From: Joerg Roedel <joro@8bytes.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jonathan Marek <jonathan@marek.ca>,
freedreno@lists.freedesktop.org, Rob Clark <robdclark@gmail.com>,
Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
Daniel Vetter <daniel@ffwll.ch>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
open list <linux-kernel@vger.kernel.org>,
iommu@lists.linux-foundation.org,
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
next prev parent reply other threads:[~2020-10-08 8:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 0:27 [PATCH 0/3] drm/msm: support for host-cached BOs Jonathan Marek
2020-10-01 0:27 ` [PATCH 1/3] drm/msm: add MSM_BO_CACHED_COHERENT Jonathan Marek
2020-10-01 23:47 ` Jordan Crouse
2020-10-01 0:27 ` [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance Jonathan Marek
2020-10-01 23:29 ` [Freedreno] " Jordan Crouse
2020-10-02 7:53 ` Christoph Hellwig
2020-10-02 12:46 ` Jonathan Marek
2020-10-05 8:29 ` Christoph Hellwig
2020-10-05 14:35 ` Jonathan Marek
2020-10-06 7:23 ` 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]
2020-10-01 0:27 ` [PATCH 3/3] drm/msm: bump up the uapi version Jonathan Marek
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