From: will.deacon@arm.com (Will Deacon) Date: Fri, 19 Feb 2016 17:13:30 +0000 Subject: [PATCH] iommu/arm-smmu-v2: Add support for 16 bit VMID In-Reply-To: <1455819817-8432-1-git-send-email-tchalamarla@caviumnetworks.com> References: <1455819817-8432-1-git-send-email-tchalamarla@caviumnetworks.com> Message-ID: <20160219171329.GO27062@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Feb 18, 2016 at 10:23:37AM -0800, tchalamarla at caviumnetworks.com wrote: > From: Tirumalesh Chalamarla > > ARM-SMMUv2 supports upto 16 bit VMID. This patch enables > 16 bit VMID when requested from device-tree. > > Signed-off-by: Tirumalesh Chalamarla > --- > .../devicetree/bindings/iommu/arm,smmu.txt | 2 ++ > drivers/iommu/arm-smmu.c | 21 ++++++++++++++++++++- > 2 files changed, 22 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > index 7180745..bb7e569 100644 > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > @@ -55,6 +55,8 @@ conditions. > aliases of secure registers have to be used during > SMMU configuration. > > +- smmu-enable-vmid16 : Enable 16 bit VMID, if allowed. Why do we need a new property for this, given that we can detect it from the ID registers? I can't think of a reason why we wouldn't use 16-bit VMIDs if they were available to us. Will