Re: [PATCH] net/iavf: check PTP capabilities during init

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Nov 21, 2025 at 03:39:37PM -0800, Jacob Keller wrote:
> Commit d21c2fe6e5a1 ("net/iavf: fix check for PF Rx timestamp support")
> added a check against whether the PF has actually enabled Rx
> timestamping in iavf_dev_info_get(). Unfortunately, this function may be
> called prior to the PTP capabilities being exchanged, which results in
> Rx timestamping not being supported.
> 
> Fix this by checking the PF PTP capabilities near the end of
> iavf_dev_init(). This ensures the VF knows the capabilities at the point
> where the iavf_dev_info_get() function can be called. Doing the check at
> init is better than inside the info callback, as the info callback is
> called many times.
> 
> The capability exchange in iavf_dev_start() is kept to ensure that
> capabilities are updated after resets.
> 
> Fixes: d21c2fe6e5a1 ("net/iavf: fix check for PF Rx timestamp support")
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> ---
> My recent fix to prevent enabling Rx timestamping on PFs which do support
> PTP capability but do not report Rx timestamping accidentally broke PFs
> which *do* support Rx timestamping. This is because the driver did not
> exchange capability before reporting its device info. Fix this by checking
> PF capabilities during iavf_dev_init().
> ---
>  drivers/net/intel/iavf/iavf_ethdev.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/intel/iavf/iavf_ethdev.c b/drivers/net/intel/iavf/iavf_ethdev.c
> index 3ef766de4704..9b07b11a6b51 100644
> --- a/drivers/net/intel/iavf/iavf_ethdev.c
> +++ b/drivers/net/intel/iavf/iavf_ethdev.c
> @@ -2887,6 +2887,14 @@ iavf_dev_init(struct rte_eth_dev *eth_dev)
>  		}
>  	}
>  
> +	/* Get PTP caps early to verify device capabilities */
> +	if (vf->vf_res->vf_cap_flags & VIRTCHNL_VF_CAP_PTP) {
> +		if (iavf_get_ptp_cap(adapter)) {
> +			PMD_INIT_LOG(ERR, "Failed to get ptp capability");
> +			goto security_init_err;
> +		}
> +	}
> +

With this code added here, do we still need to keep - or should we keep -
the existing call in iavf_dev_start()? I would have expected the call to
iavf_get_ptp_cap to be moved rather than duplicated. Is there a reason
to keep the existing call?

/Bruce