Re: [PATCH] i40e: fix the wrong PTP frequency calculation

[Yajun Deng]

On 2023/9/26 07:59, Tony Nguyen wrote:
> On 9/25/2023 12:55 AM, Yajun Deng wrote:
> > On 2023/6/28 04:20, Jacob Keller wrote:
> > > On 6/26/2023 7:26 PM, Yajun Deng wrote:
> > > > The new adjustment should be based on the base frequency, not the
> > > > I40E_PTP_40GB_INCVAL in i40e_ptp_adjfine().
> > > >
> > > > This issue was introduced in commit 3626a690b717 ("i40e: use
> > > > mul_u64_u64_div_u64 for PTP frequency calculation"), and was fixed in
> > > > commit 1060707e3809 ("ptp: introduce helpers to adjust by scaled
> > > > parts per million"). However the latter is a new feature and hasn't 
> > > > been
> > > > backported to the stable releases.
> > > >
> > > > This issue affects both v6.0 and v6.1 versions, and the v6.1 
> > > > version is
> > > > an LTS version.
>
> ...
>
> > > Thanks for finding and fixing this mistake. I think its the simplest 
> > > fix
> > > to get into the stable kernel that are broken, since taking the
> > > adjust_by_scaled_ppm version would require additional patches.
> > >
> > > Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
> > Kindly ping...
>
> As this patch looks to be for stable, you need to follow the process 
> for that. I believe your situation would fall into option 3:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#option-3 
Yes, it needs an upstream commit ID. But this patch didn't need to apply 
to the upstream.

As the commit of the patch, the issue was fixed in
commit 1060707e3809 ("ptp: introduce helpers to adjust by scaled
parts per million"). However the commit is a new feature and hasn't been
backported to the stable releases.

Therefore, the patch does not have an upstream commit ID, and only needs 
to be applied to stable.


> Thanks,
> Tony