Re: [PATCH 0/3] ata: fix deferred QC handling for port multipliers

[Niklas Cassel <cassel@kernel.org>]

Hello Tommy,

On Tue, May 05, 2026 at 05:13:41PM -0700, Tommy Kelly wrote:
> > 
> > I will also apply the FBS devicetree change (5918bf2) and test with that too.
> > 
> 
> Special thank you to Heiko for the FBS support!
> His patch setting PxCMD.FBSCP works: https://lore.kernel.org/all/20260201191804.41421-2-heiko@sntech.de/
> 
> I compiled the FBS devicetree change into u-boot (which passes the fdt to linux),
> and running on unpatched linux 6.19.12,
> FBS works, and no regressions are present.

Nice!


> Again, that is before this patch series, I see no queue_depth regression with FBS.
> As opposed to CBS which had a regression in the 6.19.x series.
> 
> I can test with this patch series + FBS if you'd like.

That would very much be appreciated if you could.

Since:
1) This series actually modifies PMP FBS behavior. Basically after this
   series, the performance should be the same as with 6.19.
   (We currently have a performance regression in mainline.)
2) I do not have a PMP with FBS available to test with.
3) I tried to reproduce your problem with a PMP with CBS, but was
   unsuccessful to reproduce it.

Thank you once again for your help!


Kind regards,
Niklas