From fd4b97246a23c1149479b88490946bcfbd28de63 Mon Sep 17 00:00:00 2001 From: Alexei Lazar Date: Wed, 23 Jul 2025 10:44:30 +0300 Subject: [PATCH] net/mlx5e: Clear Read-Only port buffer size in PBMC before update When updating the PBMC register, we read its current value, modify desired fields, then write it back. The port_buffer_size field within PBMC is Read-Only (RO). If this RO field contains a non-zero value when read, attempting to write it back will cause the entire PBMC register update to fail. This commit ensures port_buffer_size is explicitly cleared to zero after reading the PBMC register but before writing back the modified value. This allows updates to other fields in the PBMC register to succeed. Fixes: 0696d60853d5 ("net/mlx5e: Receive buffer configuration") Signed-off-by: Alexei Lazar Reviewed-by: Yael Chemla Signed-off-by: Tariq Toukan Link: https://patch.msgid.link/1753256672-337784-2-git-send-email-tariqt@nvidia.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c b/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c index 8e25f4ef5ccce..5ae787656a7ca 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/port_buffer.c @@ -331,6 +331,9 @@ static int port_set_buffer(struct mlx5e_priv *priv, if (err) goto out; + /* RO bits should be set to 0 on write */ + MLX5_SET(pbmc_reg, in, port_buffer_size, 0); + err = mlx5e_port_set_pbmc(mdev, in); out: kfree(in); -- 2.47.2