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

[Niklas Cassel <cassel@kernel.org>]

Hello John,

On Mon, May 04, 2026 at 08:27:06AM +0100, John Garry wrote:
> On 01/05/2026 19:42, Niklas Cassel wrote:
> > On Fri, May 01, 2026 at 03:19:03PM +0100, John Garry wrote:
> > > On 01/05/2026 13:54, Niklas Cassel wrote:
> > > 
> > > As I understand, this deferred QC scheme was intended to solve starvation
> > > problems for multiqueue SAS HBAs (using libsas-based drivers). libsas has no
> > > port multiplier support, so I wonder why we make deferred QC scheme work for
> > > port multiplier, i.e. non-libsas scenario.
> > 
> > Are you certain that there are no libsas HBAs that support port
> > multipliers?
> 
> No, I am just saying that libsas does not support port multipliers, see
> earlier effort @ https://lore.kernel.org/linux-scsi/1398346023-10225-1-git-send-email-yxlraid@gmail.com/
> 
> See this today:
> 
> int sas_discover_sata(struct domain_device *dev)
> {
> 	if (dev->dev_type == SAS_SATA_PM)
> 		return -ENODEV;
>

I see, thank you for the information!

Will send a V2 soon.


Kind regards,
Niklas