From: Ivan Vecera <ivecera@redhat.com>
To: Tariq Toukan <tariqt@nvidia.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>
Cc: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>,
Carolina Jubran <cjubran@nvidia.com>,
Gal Pressman <gal@nvidia.com>, Jiri Pirko <jiri@nvidia.com>,
Jiri Pirko <jiri@resnulli.us>, Leon Romanovsky <leon@kernel.org>,
open list <linux-kernel@vger.kernel.org>,
linux-rdma@vger.kernel.org, Mark Bloch <mbloch@nvidia.com>,
Saeed Mahameed <saeedm@nvidia.com>,
Vadim Fedorenko <vadim.fedorenko@linux.dev>
Subject: Re: [PATCH net] net/mlx5: DPLL, fix fractional frequency offset scaling
Date: Mon, 19 Oct 2026 19:19:51 +0200 [thread overview]
Message-ID: <98c195a3-9cf4-4d4f-80c2-5186055454fe@redhat.com> (raw)
In-Reply-To: <20261015074035.1092340-1-tariqt@nvidia.com>
On 10/15/26 09:40, Tariq Toukan wrote:
> From: Carolina Jubran <cjubran@nvidia.com>
>
> The frequency_diff is reported by firmware in parts-per-trillion, which
> is exactly what the DPLL core now expects from the ffo_get callback.
>
> Commit bc443c253fcd ("dpll: expose fractional frequency offset in ppt")
> switched the callback contract to ppt but assumed frequency_diff was in
> ppm and scaled it by 1000000 to "convert" it. Since the value was
> already ppt, this makes both exported attributes wrong.
>
> Report frequency_diff as is and let the core divide it down for the
> legacy ppm attribute.
>
> Fixes: f035dca34ede ("net/mlx5: DPLL, Implement fractional frequency offset get pin op")
> Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
> ---
It’s a pity we didn’t implement FFO in ppt units right from the start... We
wouldn’t have to carry a duplicate attribute in ppm units now for the sake of
backward compatibility.
Anyway...
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
next prev parent reply other threads:[~2026-10-19 17:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-15 7:40 Tariq Toukan
2026-10-15 7:43 ` netdev-bot+sinfo
2026-10-15 9:28 ` Carolina Jubran
2026-10-15 10:49 ` Daniel Machon
2026-10-19 17:19 ` Ivan Vecera [this message]
2026-10-20 13:20 ` patchwork-bot+netdevbpf
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