2023-05-17 11:06:13

by Ilpo Järvinen

Subject: [PATCH v2 6/9] net/mlx5: Use RMW accessors for changing LNKCTL

Don't assume that only the driver would be accessing LNKCTL of the
upstream bridge. ASPM policy changes can trigger write to LNKCTL
outside of driver's control.

Use RMW capability accessors which do proper locking to avoid losing
concurrent updates to the register value.

Fixes: eabe8e5e88f5 ("net/mlx5: Handle sync reset now event")
Suggested-by: Lukas Wunner <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Cc: [email protected]
---
drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c b/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
index 50022e7565f1..f202150a5093 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
@@ -332,16 +332,11 @@ static int mlx5_pci_link_toggle(struct mlx5_core_dev *dev)
pci_cfg_access_lock(sdev);
}
/* PCI link toggle */
- err = pci_read_config_word(bridge, cap + PCI_EXP_LNKCTL, &reg16);
- if (err)
- return err;
- reg16 |= PCI_EXP_LNKCTL_LD;
- err = pci_write_config_word(bridge, cap + PCI_EXP_LNKCTL, reg16);
+ err = pcie_capability_set_word(bridge, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_LD);
if (err)
return err;
msleep(500);
- reg16 &= ~PCI_EXP_LNKCTL_LD;
- err = pci_write_config_word(bridge, cap + PCI_EXP_LNKCTL, reg16);
+ err = pcie_capability_clear_word(bridge, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_LD);
if (err)
return err;

--
2.30.2

2023-05-17 11:50:08

by Moshe Shemesh

Subject: Re: [PATCH v2 6/9] net/mlx5: Use RMW accessors for changing LNKCTL

On 5/17/2023 1:52 PM, Ilpo Järvinen wrote:
> Don't assume that only the driver would be accessing LNKCTL of the
> upstream bridge. ASPM policy changes can trigger write to LNKCTL
> outside of driver's control.
>
> Use RMW capability accessors which do proper locking to avoid losing
> concurrent updates to the register value.
>
> Fixes: eabe8e5e88f5 ("net/mlx5: Handle sync reset now event")
> Suggested-by: Lukas Wunner<[email protected]>
> Signed-off-by: Ilpo Järvinen<[email protected]>
> Cc:[email protected]
Reviewed-by: Moshe Shemesh <[email protected]>

Thanks!