From: Christoph Hellwig <hch@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
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>
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 15 Oct 2020 07:55:32 +0100 [thread overview]
Message-ID: <20201015065532.GA15371@infradead.org> (raw)
In-Reply-To: <c3baadae-8e20-86a6-44f5-4571a8d3035e@arm.com>
On Tue, Oct 13, 2020 at 02:42:38PM +0100, Robin Murphy wrote:
> I still think this situation would be best handled with a variant of
> dma_ops_bypass that also guarantees to bypass SWIOTLB, and can be set
> automatically when attaching to an unmanaged IOMMU domain.
dma_ops_bypass should mostly do the right thing as-is. swiotlb bouncing
is triggered of two things:
1) the dma_mask. This is under control of the driver, and obviously
if it is too small for a legit reason we can't just proceed
2) force_dma_unencrypted() - we'd need to do an opt-out here, either
by a flag or by being smart and looking for an attached iommu on
the device
> That way the
> device driver can make DMA API calls in the appropriate places that do the
> right thing either way, and only needs logic to decide whether to use the
> returned DMA addresses directly or ignore them if it knows they're
> overridden by its own IOMMU mapping.
I'd be happy to review patches for this.
next prev parent reply other threads:[~2020-10-15 6:55 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 [this message]
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
2020-10-01 0:27 ` [PATCH 3/3] drm/msm: bump up the uapi version Jonathan Marek
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