Re: [PATCH 1/2] net/iavf: check if PF actually indicates Rx timestamps

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

On Thu, Nov 13, 2025 at 01:33:44PM -0800, Jacob Keller wrote:
> The iavf driver has support for hardware Rx timestamps since commit h
> b5cd735132f6 ("net/iavf: enable Rx timestamp on flex descriptor").
> 
> To enable this, the VF must first negotiate PTP capabilities with the PF
> by sending the VIRTCHNL_OP_1588_PTP_GET_CAPS command, with the requested
> capabilities. The PF will respond with the actually supported subset of
> capabilities.
> 
> The PF may not actually enable Rx timestamping, even if it reports the
> overall PTP capability support. If this happens, the iavf driver logic
> will incorrectly report that Rx timestamps can be enabled despite being
> rejected by the PF.
> 
> This is unlikely in practice, as most PFs which support the
> VIRTCHNL_VF_CAP_PTP will support Rx timestamping. However, there are
> some cases where this may not be true.
> 
> Check that the PF actually reports the Rx timestamping capability
> instead of assuming it is enabled. Doing so prevents the DPDK
> application from attempting to enable Rx timestamps when they won't
> actually be enabled.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> ---

Fixes: b5cd735132f6 ("net/iavf: enable Rx timestamp on flex descriptor")

Acked-by: Bruce Richardson <bruce.richardson@intel.com>