Re: [PATCH net v2 2/5] renesas: reject PTP_STRICT_FLAGS as unsupported

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Jacob,

Thanks for your work.

On 2025-03-12 15:15:51 -0700, Jacob Keller wrote:
> The ravb_ptp_extts() function checks the flags coming from the
> PTP_EXTTS_REQUEST ioctl, to ensure that future flags are not accepted on
> accident.
> 
> This was updated to 'honor' the PTP_STRICT_FLAGS in commit 6138e687c7b6
> ("ptp: Introduce strict checking of external time stamp options.").
> However, the driver does not *actually* validate the flags.
> 
> I originally fixed this driver to reject future flags in commit
> 592025a03b34 ("renesas: reject unsupported external timestamp flags"). It
> is still unclear whether this hardware timestamps the rising, falling, or
> both edges of the input signal.
> 
> Accepting requests with PTP_STRICT_FLAGS is a bug, as this could lead to
> users mistakenly assuming a request with PTP_RISING_EDGE actually
> timestamps the rising edge only.
> 
> Reject requests with PTP_STRICT_FLAGS (and hence all PTP_EXTTS_REQUEST2
> requests) until someone with access to the datasheet or hardware knowledge
> can confirm the timestamping behavior and update this driver.
> 
> Fixes: 6138e687c7b6 ("ptp: Introduce strict checking of external time stamp options.")
> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/net/ethernet/renesas/ravb_ptp.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
> index 6e4ef7af27bf31ab2aad8e06a65e0ede6046e3c0..b4365906669f3bd40953813e263aeaafd2e1eb70 100644
> --- a/drivers/net/ethernet/renesas/ravb_ptp.c
> +++ b/drivers/net/ethernet/renesas/ravb_ptp.c
> @@ -179,8 +179,7 @@ static int ravb_ptp_extts(struct ptp_clock_info *ptp,
>  	/* Reject requests with unsupported flags */
>  	if (req->flags & ~(PTP_ENABLE_FEATURE |
>  			   PTP_RISING_EDGE |
> -			   PTP_FALLING_EDGE |
> -			   PTP_STRICT_FLAGS))
> +			   PTP_FALLING_EDGE))
>  		return -EOPNOTSUPP;
>  
>  	if (req->index)
> 
> -- 
> 2.48.1.397.gec9d649cc640
> 

-- 
Kind Regards,
Niklas Söderlund