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From: Will Deacon <will@kernel.org>
To: Rob Clark <robdclark@gmail.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Rob Clark <robdclark@chromium.org>,
	Jonathan Marek <jonathan@marek.ca>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Mamta Shukla <mamtashukla555@gmail.com>,
	Bartosz Golaszewski <brgl@bgdev.pl>,
	Joerg Roedel <jroedel@suse.de>, Arnd Bergmann <arnd@arndb.de>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Abhinav Kumar <abhinavk@codeaurora.org>,
	Bruce Wang <bzwang@chromium.org>,
	Alexios Zavras <alexios.zavras@intel.com>,
	Sean Paul <seanpaul@chromium.org>,
	Jeykumar Sankaran <jsanka@codeaurora.org>,
	Allison Randal <allison@lohutok.net>,
	Boris Brezillon <bbrezillon@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	open list <linux-kernel@vger.kernel.org>,
	"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
	Joerg Roedel <joro@8bytes.org>,
	" <iommu@lists.linux-foundation.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Joe Perches <joe@perches.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"open list:DRM DRIVER FOR MSM ADRENO GPU"
	<freedreno@lists.freedesktop.org>,
	Georgi Djakov <georgi.djakov@linaro.org>,
	Sravanthi Kollukuduru <skolluku@codeaurora.org>
Subject: Re: [PATCH v3 0/2] iommu: handle drivers that manage iommu directly
Date: Tue, 17 Sep 2019 14:36:37 +0100
Message-ID: <20190917133637.urqphz5drzmugern@willie-the-truck> (raw)
In-Reply-To: <CAF6AEGv5WtwOuUE-+koL3SxuoXxcT5n=EooD7G_4YRh34HFTwQ@mail.gmail.com>

On Tue, Sep 10, 2019 at 10:10:49AM -0700, Rob Clark wrote:
> On Tue, Sep 10, 2019 at 9:34 AM Robin Murphy <robin.murphy@arm.com> wrote:
> > On 06/09/2019 22:44, Rob Clark wrote:
> > > NOTE that in discussion of previous revisions, RMRR came up.  This is
> > > not really a replacement for RMRR (nor does RMRR really provide any
> > > more information than we already get from EFI GOP, or DT in the
> > > simplefb case).  I also don't see how RMRR could help w/ SMMU handover
> > > of CB/SMR config (Bjorn's patchset[1]) without defining new tables.
> >
> > The point of RMRR-like-things is that they identify not just the memory
> > region but also the specific device accessing them, which means the
> > IOMMU driver knows up-front which IDs etc. it must be careful not to
> > disrupt. Obviously for SMMU that *would* be some new table (designed to
> > encompass everything relevant) since literal RMRRs are specifically an
> > Intel VT-d thing.
> 
> Perhaps I'm not looking in the right place, but the extent of what I
> could find about RMRR tables was:
> 
> https://github.com/tianocore/edk2/blob/master/MdePkg/Include/IndustryStandard/DmaRemappingReportingTable.h#L122
> 
> I couldn't really see how that specifies the device.  But entirely
> possible that I'm not seeing the whole picture.

I don't think anybody was planning to implement RMRR "as-is" for arm64, so
you might be better off looking at the proposal from Thierry, although it
has some issues that are still to be resolved:

http://lkml.kernel.org/r/20190829111407.17191-1-thierry.reding@gmail.com

Will
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Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 21:44 Rob Clark
2019-09-06 21:44 ` [PATCH v2 1/2] iommu: add support for drivers that manage iommu explicitly Rob Clark
2019-09-10  8:14   ` Joerg Roedel
2019-09-10 15:34     ` Rob Clark
2019-09-10 16:51       ` Robin Murphy
2019-09-06 21:44 ` [PATCH v2 2/2] drm/msm: mark devices where iommu is managed by driver Rob Clark
2019-09-10 16:34 ` [PATCH v3 0/2] iommu: handle drivers that manage iommu directly Robin Murphy
2019-09-10 17:10   ` Rob Clark
2019-09-17 13:36     ` Will Deacon [this message]

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