Re: [PATCH] of: property: Add device link support for "iommu-map"

From: Will Deacon <will@kernel.org>
To: Rob Herring <robh@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	devicetree@vger.kernel.org, iommu@lists.linuxfoundation.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Saravana Kannan <saravanak@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	ard.biesheuvel@linaro.org
Subject: Re: [PATCH] of: property: Add device link support for "iommu-map"
Date: Fri, 22 Nov 2019 14:55:25 +0000	[thread overview]
Message-ID: <20191122145525.GA14153@willie-the-truck> (raw)
In-Reply-To: <CAL_JsqJm+6Cg4JfG1EzRMJ2hyPV1O8WbitjGC=XMvZRDD+=OGw@mail.gmail.com>

[+Ard]

Hi Rob,

On Fri, Nov 22, 2019 at 08:47:46AM -0600, Rob Herring wrote:
> On Wed, Nov 20, 2019 at 1:00 PM Will Deacon <will@kernel.org> wrote:
> >
> > Commit 8e12257dead7 ("of: property: Add device link support for iommus,
> > mboxes and io-channels") added device link support for IOMMU linkages
> > described using the "iommus" property. For PCI devices, this property
> > is not present and instead the "iommu-map" property is used on the host
> > bridge node to map the endpoint RequesterIDs to their corresponding
> > IOMMU instance.
> >
> > Add support for "iommu-map" to the device link supplier bindings so that
> > probing of PCI devices can be deferred until after the IOMMU is
> > available.
> >
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Rob Herring <robh@kernel.org>
> > Cc: Saravana Kannan <saravanak@google.com>
> > Cc: Robin Murphy <robin.murphy@arm.com>
> > Signed-off-by: Will Deacon <will@kernel.org>
> > ---
> >
> > Applies against driver-core/driver-core-next.
> > Tested on AMD Seattle (arm64).
> 
> Guess that answers my question whether anyone uses Seattle with DT.
> Seattle uses the old SMMU binding, and there's not even an IOMMU
> associated with the PCI host. I raise this mainly because the dts
> files for Seattle either need some love or perhaps should be removed.

I'm using the new DT bindings on my Seattle, thanks to the firmware fairy
(Ard) visiting my flat with a dediprog. The patches I've posted to enable
modular builds of the arm-smmu driver require that the old binding is
disabled [1].

> No issues with the patch itself though. I'll queue it after rc1.

Thanks, although I think Greg has already queued it [2] due to the
dependencies on other patches in his tree.

Will

[1] https://lore.kernel.org/lkml/20191121114918.2293-14-will@kernel.org/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git/commit/?h=driver-core-next&id=e149573b2f84d0517648dafc0db625afa681ed54