[Intel-wired-lan] [PATCH net v2 1/5] igb: reject invalid external timestamp requests for 82580-based HW

[Simon Horman]

On Wed, Mar 12, 2025 at 03:15:50PM -0700, Jacob Keller wrote:
> The igb_ptp_feature_enable_82580 function correctly checks that unknown
> flags are not passed to the function. However, it does not actually check
> PTP_RISING_EDGE or PTP_FALLING_EDGE when configuring the external timestamp
> function.
> 
> The data sheet for the 82580 product says:
> 
>   Upon a change in the input level of one of the SDP pins that was
>   configured to detect Time stamp events using the TSSDP register, a time
>   stamp of the system time is captured into one of the two auxiliary time
>   stamp registers (AUXSTMPL/H0 or AUXSTMPL/H1).
> 
>   For example to define timestamping of events in the AUXSTMPL0 and
>   AUXSTMPH0 registers, Software should:
> 
>   1. Set the TSSDP.AUX0_SDP_SEL field to select the SDP pin that detects
>      the level change and set the TSSDP.AUX0_TS_SDP_EN bit to 1.
> 
>   2. Set the TSAUXC.EN_TS0 bit to 1 to enable timestamping
> 
> The same paragraph is in the i350 and i354 data sheets.
> 
> The wording implies that the time stamps are captured at any level change.
> There does not appear to be any way to only timestamp one edge of the
> signal.
> 
> Reject requests which do not set both PTP_RISING_EDGE and PTP_FALLING_EDGE
> when operating under PTP_STRICT_FLAGS mode via PTP_EXTTS_REQUEST2.
> 
> Fixes: 38970eac41db ("igb: support EXTTS on 82580/i354/i350")
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski at linux.intel.com>
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>

Reviewed-by: Simon Horman <horms at kernel.org>