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

[Tommy Kelly <linux@tkel.ly>]

On 5/1/26 05:54, Niklas Cassel wrote:
> Hello all,
> 
> Tommy Kelly reported a regression with PMP that use CBS:
> https://lore.kernel.org/linux-ide/ce09cc21-a8e9-4845-b205-35411e22fba9@tkel.ly/

> 
> Tommy, it would be nice if you could apply this series and see if it solves
> your problem. Right now the series is compile tested only.
> 
> 
> Niklas Cassel (3):
>   ata: libata-pmp: fix ata_pmp_qc_defer_cmd_switch()
>   ata: libata-scsi: do not use the deferred QC feature on PMPs with CBS
>   ata: libata-scsi: do not needlessly defer commands when using PMP with
>     FBS
> 
>  drivers/ata/libata-core.c | 16 +++++++---
>  drivers/ata/libata-eh.c   |  8 ++---
>  drivers/ata/libata-pmp.c  | 13 +++++---
>  drivers/ata/libata-scsi.c | 66 ++++++++++++++++++++++-----------------
>  include/linux/libata.h    |  6 ++--
>  5 files changed, 64 insertions(+), 45 deletions(-)
> 

Hi Niklas,

Yes, this patch series fixed the regression for me with a CBS Port Multiplier.

Here are the commits I tested with:

> (HEAD -> fedora-7.0-libata) ata: libata-scsi: do not needlessly defer commands when using PMP with FBS
> ata: libata-scsi: do not use the deferred QC feature on PMPs with CBS
> ata: libata-pmp: fix ata_pmp_qc_defer_cmd_switch()
> ata: ahci: fail probe if BAR too small for claimed ports
> ata: libahci: use ahci_nr_ports() helper
> ata: pata_parport: switch to dynamic root device
> Merge remote-tracking branch 'libata/for-7.1' into fedora-7.0-libata
> (tag: kernel-7.0.3-0, kernel-ark/fedora-7.0, fedora-7.0) [redhat] kernel-7.0.3-0
> Merge Linux v7.0.3
> (tag: v7.0.3, kernel-ark/linux-7.0.y, linux-7.0.y) Linux 7.0.3

And here's some logs showing ata_id (non-NCQ) resolving immediately.
After, I'm able to boot and mount and use the filesystem no problem.
No errors and no timeouts.

> Mar 12 17:00:10 localhost kernel: ahci-dwc fc800000.sata: port 0 is not capable of FBS
> May 02 17:12:39 (udev-worker)[874]: sdd: Starting 'ata_id --export /dev/sdd'
> May 02 17:12:39 (udev-worker)[874]: sdd: 'ata_id --export /dev/sdd'(out) 'ID_ATA=1'
> May 02 17:12:39 (udev-worker)[874]: sdd: Process 'ata_id --export /dev/sdd' succeeded.

> $ cat /sys/block/sd*/device/queue_depth
> 32
> 32
> 32
> 32
> 32

I will also apply the FBS devicetree change (5918bf2) and test with that too.

Thank you for your work on this!

- Tommy