linux-kernel - Re: [PATCH net v2] net: sparx5: Fix invalid timestamps

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Message-ID: <20240917061305.47x26cdfv3fr7rzh@DEN-DL-M31836.microchip.com>
Date: Tue, 17 Sep 2024 08:13:05 +0200
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: Aakash Menon <aakash.r.menon@...il.com>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <lars.povlsen@...rochip.com>,
	<Steen.Hegelund@...rochip.com>, <daniel.machon@...rochip.com>,
	<UNGLinuxDriver@...rochip.com>, <aakash.menon@...tempis.com>,
	<horms@...nel.org>, <netdev@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net v2] net: sparx5: Fix invalid timestamps

The 09/16/2024 22:18, Aakash Menon wrote:
> 
> 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.

Thanks for changes. I think it look good.
Reviewed-by: Horatiu Vultur <horatiu.vultur@...rochip.com>

> 
> Fixes: 70dfe25cd866 ("net: sparx5: Update extraction/injection for timestamping")
> Signed-off-by: Aakash Menon <aakash.menon@...tempis.com>
> ---
> v2:
> - Wrap patch descriptions at 75 characters wide.
> - Use GENMASK(5,0) instead of masking with 0x3F
> - Update Fixes tag to be on the same line
> - Link to v1 -https://lore.kernel.org/r/20240913193357.21899-1-aakash.menon@protempis.com
> 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..70427643f777 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] & GENMASK(5, 0)) << 24) |
>                 ((u64)xtr_hdr[3] << 16) |
>                 ((u64)xtr_hdr[4] <<  8) |
>                 ((u64)xtr_hdr[5] <<  0);
> --
> 2.46.0
> 

-- 
/Horatiu