netdev - [PATCH RFC 1/2] net/mlx5: Request PCIe AtomicOps enabled for all 3 sizes

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Message-Id: <20251105-mlxatomics-v1-1-10c71649e08d@linux.ibm.com>
Date: Wed, 05 Nov 2025 18:55:13 +0100
From: Gerd Bayer <gbayer@...ux.ibm.com>
To: Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>,
        Tariq Toukan <tariqt@...dia.com>, Mark Bloch <mbloch@...dia.com>,
        Andrew Lunn <andrew+netdev@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Jay Cornwall <Jay.Cornwall@....com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        Alexander Schmidt <alexs@...ux.ibm.com>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        Gerd Bayer <gbayer@...ux.ibm.com>
Subject: [PATCH RFC 1/2] net/mlx5: Request PCIe AtomicOps enabled for all 3
 sizes

Pass fully populated capability bit-mask requesting support for all 3
sizes of AtomicOps at once when attempting to enable AtomicOps for PCI
function.

When called individually, pci_enable_atomic_ops_to_root() may enable the
device to send requests as soon as one size is supported. According to
PCIe Spec 7.0 Section 6.15.3.1 support of 32-bit and 64-bit AtomicOps
completer capabilities are tied together for root-ports. Only the
128-bit/CAS completer capabilities is an optional feature, but still we
might end up end up enabling AtomicOps despite 128-bit/CAS is not
supported at the root-port.

Signed-off-by: Gerd Bayer <gbayer@...ux.ibm.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
index 70c156591b0ba9c61dd99818043003e50e177590..69152a9dae2be07e023fa42fd9ef010c8b255c4c 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
@@ -934,9 +934,9 @@ static int mlx5_pci_init(struct mlx5_core_dev *dev, struct pci_dev *pdev,
 		goto err_clr_master;
 	}
 
-	if (pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP32) &&
-	    pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP64) &&
-	    pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP128))
+	if (pci_enable_atomic_ops_to_root(pdev, PCI_EXP_DEVCAP2_ATOMIC_COMP32 |
+						PCI_EXP_DEVCAP2_ATOMIC_COMP64 |
+						PCI_EXP_DEVCAP2_ATOMIC_COMP128))
 		mlx5_core_dbg(dev, "Enabling pci atomics failed\n");
 
 	dev->iseg_base = dev->bar_addr;

-- 
2.48.1