Re: [PATCH net] net: stmmac: ptp: fix support for PTP_EXTTS_REQUEST2 ioctl

[Lorenzo Bianconi]

> Commit 7c571ac57d9d ("net: ptp: introduce .supported_extts_flags to
> ptp_clock_info") modified the PTP core to validate the supported flags
> of external timestamp requests, rather than relying on each driver to
> check them.
> 
> stmmac_enable() and dwmac1000_ptp_enable() ignore the flags, and
> neither stmmac_ptp_clock_ops nor dwmac1000_ptp_clock_ops was given any
> .supported_extts_flags. Since PTP_EXTTS_REQUEST2 always implies
> PTP_STRICT_FLAGS, the core now rejects every PTP_EXTTS_REQUEST2 for
> this driver with -EOPNOTSUPP, where before that commit the same
> requests succeeded. Only the PTP_EXTTS_REQUEST ioctl still works.
> 
> Tests on an NXP i.MX 8M Plus (FRDM-IMX8MPLUS, GMAC 5.10a) show that the
> auxiliary snapshot inputs timestamp just the rising edge. The reference
> manuals for the STM32MP13 (GMAC 4.20a) and the Cyclone V HPS (GMAC
> 3.70a, which uses dwmac1000_ptp_clock_ops) say the same.
> 
> Encode this in .supported_extts_flags. A PTP_EXTTS_REQUEST2 for the
> rising edge then succeeds, and one for the falling edge or for both
> edges fails with -EOPNOTSUPP.
> 
> Fixes: 7c571ac57d9d ("net: ptp: introduce .supported_extts_flags to ptp_clock_info")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: James Clark <jjc@xxxxxxxxxx>

Reviewed-by: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxxxxxxxx>

> ---
> I used an LLM coding assistant to help prepare this patch.
> 
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> index a37405534beb..31a66e855d6b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
> @@ -277,6 +277,7 @@ const struct ptp_clock_info stmmac_ptp_clock_ops = {
>  	.n_per_out = 0, /* will be overwritten in stmmac_ptp_register */
>  	.n_pins = 0,
>  	.pps = 0,
> +	.supported_extts_flags = PTP_RISING_EDGE | PTP_STRICT_FLAGS,
>  	.adjfine = stmmac_adjust_freq,
>  	.adjtime = stmmac_adjust_time,
>  	.gettimex64 = stmmac_get_timex,
> @@ -294,6 +295,7 @@ const struct ptp_clock_info dwmac1000_ptp_clock_ops = {
>  	.n_per_out = 0,
>  	.n_pins = 0,
>  	.pps = 0,
> +	.supported_extts_flags = PTP_RISING_EDGE | PTP_STRICT_FLAGS,
>  	.adjfine = stmmac_adjust_freq,
>  	.adjtime = stmmac_adjust_time,
>  	.gettimex64 = stmmac_get_timex,
> -- 
> 2.56.0
> 
>

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