From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Murphy Subject: Re: [PATCH 0/2] iommu/arm-smmu: Add an optional "input-address-size" property Date: Fri, 11 Oct 2019 10:16:28 +0100 Message-ID: References: <20191011034609.13319-1-nicoleotsuka@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20191011034609.13319-1-nicoleotsuka@gmail.com> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Nicolin Chen , joro@8bytes.org, robh+dt@kernel.org, mark.rutland@arm.com, will@kernel.org Cc: vdumpa@nvidia.com, iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On 2019-10-11 4:46 am, Nicolin Chen wrote: > This series of patches add an optional DT property to allow an SoC to > specify how many bits being physically connected to its SMMU instance, > depending on the SoC design. This has come up before, and it doesn't work in general because a single SMMU instance can have many master interfaces, with potentially different sizes of address bus wired up to each. It's also a conceptually-wrong approach anyway, since this isn't a property of the SMMU; it's a property of the interconnect(s) upstream of the SMMU. IIRC you were working on Tegra - if so, Thierry already has a plan, see this thread: https://lore.kernel.org/linux-arm-kernel/20190930133510.GA1904140@ulmo/ Robin. > > Nicolin Chen (2): > dt-bindings: arm-smmu: Add an optional "input-address-size" property > iommu/arm-smmu: Read optional "input-address-size" property > > Documentation/devicetree/bindings/iommu/arm,smmu.txt | 7 +++++++ > drivers/iommu/arm-smmu.c | 10 ++++++++-- > 2 files changed, 15 insertions(+), 2 deletions(-) >