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[159.2.73.22]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8d028090f43sm711572985a.45.2026.03.30.15.26.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2026 15:26:32 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w7L43-00000005H5o-0vBI; Mon, 30 Mar 2026 19:26:31 -0300 Date: Mon, 30 Mar 2026 19:26:31 -0300 From: Jason Gunthorpe To: Bjorn Helgaas Cc: Gerd Bayer , Alex Deucher , Christian =?utf-8?B?S8O2bmln?= , Selvin Xavier , Kalesh AP , Leon Romanovsky , Michal Kalderon , Saeed Mahameed , Tariq Toukan , Mark Bloch , Bjorn Helgaas , Jay Cornwall , Felix Kuehling , Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Christian Borntraeger , Niklas Schnelle , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Alexander Schmidt , linux-s390@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH v7 1/3] PCI: AtomicOps: Do not enable requests by RCiEPs Message-ID: <20260330222631.GF246076@ziepe.ca> References: <20260330-fix_pciatops-v7-1-f601818417e8@linux.ibm.com> <20260330214253.GA92498@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260330214253.GA92498@bhelgaas> On Mon, Mar 30, 2026 at 04:42:53PM -0500, Bjorn Helgaas wrote: > [+to amdgpu, bnxe_re, mlx5 IB, qedr, mlx5 maintainers] > > On Mon, Mar 30, 2026 at 03:09:44PM +0200, Gerd Bayer wrote: > > Since root complex integrated end points (RCiEPs) attach to a bus that > > has no bridge device describing the root port, the capability to > > complete AtomicOps requests cannot be determined with PCIe methods. > > > > Change default of pci_enable_atomic_ops_to_root() to not enable > > AtomicOps requests on RCiEPs. > > I know I suggested this because there's nothing explicit that tells us > whether the RC supports atomic ops from RCiEPs [1]. But I'm concerned > that GPUs, infiniband HCAs, and NICs that use atomic ops may be > implemented as RCiEPs and would be broken by this. AFAIK none of the NICs are integrated into root complexes in their topology model.. Jason