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Thu, 15 Aug 2024 06:59:53 -0700 (PDT) Received: from ziepe.ca ([128.77.69.90]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6bf6fef3124sm6542716d6.123.2024.08.15.06.59.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Aug 2024 06:59:52 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1seb15-003IAo-L0; Thu, 15 Aug 2024 10:59:51 -0300 Date: Thu, 15 Aug 2024 10:59:51 -0300 From: Jason Gunthorpe To: Robin Murphy Cc: Mostafa Saleh , linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, will@kernel.org, joro@8bytes.org, jean-philippe@linaro.org, nicolinc@nvidia.com, mshavit@google.com Subject: Re: [PATCH v2] iommu/arm-smmu-v3: Match Stall behaviour for S2 Message-ID: <20240815135951.GM3468552@ziepe.ca> References: <20240814145633.2565126-1-smostafa@google.com> <20240814155151.GB3468552@ziepe.ca> <91d6574d-c67e-484c-ad96-91c9fd3d0c43@arm.com> <20240815125919.GH3468552@ziepe.ca> <43290d6c-004d-423c-822c-7b2558badcee@arm.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43290d6c-004d-423c-822c-7b2558badcee@arm.com> On Thu, Aug 15, 2024 at 02:41:52PM +0100, Robin Murphy wrote: > Unfortunately we can't do that, because there *are* RCiEP devices whose data > interfaces are native AMBA, and thus for whom stalling is not actually a > protocol violation as it would be on a real PCIe transport layer; > correspondingly, it's *because* they are not true PCIe devices that they > can't support ATS, and thus need stall support in order to do SVA, so things > should still work out OK in practice. I wondered if that would be the case. Looks like if we want to do anything then arm_smmu_ats_supported() would be the right place. > > if (dev_is_pci(dev)) { > > > > Though I have no idea how the GPU driver that wants to use this > > works - it doesn't seem to be intree :\ > > It's not a GPU: drivers/crypto/hisilicon/zip/ Ohhhh.. so it goes through uacce, I see. Jason