[PATCH net] net: sparx5: Fix invalid timestamps

[Horatiu Vultur]

The 09/15/2024 22:18, Aakash Menon wrote:
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> Bit 270-271 are occasionally unexpectedly set by the hardware. This issue
> was observed with 10G SFPs causing huge time errors (> 30ms) in PTP. Only
> 30 bits are needed for the nanosecond part of the timestamp, clear 2 most
> significant bits before extracting timestamp from the internal frame
> header.
> 
> Fixes: 70dfe25cd866 ("net: sparx5: Update extraction/injection for
> timestamping")
> Signed-off-by: Aakash Menon <aakash.menon at protempis.com>

There are some small issues/comments with this patch:
1. The Fixes tag should still be on one line even if it is longer than
75 columns, so the robots can find it.
2. Please use GENMASK(5, 0) instead of 0x3f.

> ---
>  drivers/net/ethernet/microchip/sparx5/sparx5_packet.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
> index f3f5fb420468..a05263488851 100644
> --- a/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
> +++ b/drivers/net/ethernet/microchip/sparx5/sparx5_packet.c
> @@ -45,8 +45,12 @@ void sparx5_ifh_parse(u32 *ifh, struct frame_info *info)
>         fwd = (fwd >> 5);
>         info->src_port = FIELD_GET(GENMASK(7, 1), fwd);
> 
> +       /*
> +        * Bit 270-271 are occasionally unexpectedly set by the hardware,
> +        * clear bits before extracting timestamp
> +        */
>         info->timestamp =
> -               ((u64)xtr_hdr[2] << 24) |
> +               ((u64)(xtr_hdr[2] & 0x3F) << 24) |
>                 ((u64)xtr_hdr[3] << 16) |
>                 ((u64)xtr_hdr[4] <<  8) |
>                 ((u64)xtr_hdr[5] <<  0);
> --
> 2.46.0
> 

-- 
/Horatiu