Re: [PATCH V3 13/20] cxl/mem: Refactor cxl pmem region auto-assembling

[Neeraj Kumar]

On 12/11/25 08:55AM, Dave Jiang wrote:
>

<snip>

> > During cxl_pci_probe() we call devm_cxl_add_memdev(struct cxl_memdev_ops *ops)
> > where function pointer as ops gets registered which gets called in cxl_mem_probe()
> > using cxlmd->ops->probe()
> >
> > The probe callback runs after the port topology is successfully attached for
> > the given memdev.
> >
> > So to use this infra we have to pass cxl_region_discovery() as ops parameter
> > of devm_cxl_add_memdev() getting called from cxl_pci_probe().
> >  
> > In this patch-set cxl_region_discovery() signature is different from cxlmd->ops->probe()
> >
> >    {{{
> >     void cxl_region_discovery(struct cxl_port *port)
> >     {
> >             device_for_each_child(&port->dev, NULL, discover_region);
> >     }
> >
> >     struct cxl_memdev_ops {
> >             int (*probe)(struct cxl_memdev *cxlmd);
> >     };
> >    }}}
> >
> > Even after changing the signature of cxl_region_discovery() as per cxlmd->ops->probe()
> > may create problem as when the ops->probe() fails, then it will halts the probe sequence
> > of cxl_pci_probe()
> >
> > It is because discover_region() may fail if two memdevs are participating into one region
>
> While discover_region() may fail, the return value is ignored. The current code disregards failures from device_for_each_child(). And also above, cxl_region_discovery() returns void. So I don't follow how ops->probe() would fail if we ignore errors from discover_region().
>
> DJ

Hi Dave,

Yes, you are correct. We can just change signature of cxl_region_discovery() as per
cxlmd->ops->probe(), anyway we are ignoring errors from discover_region().
With this change we can directly register cxl_region_discovery() with
devm_cxl_add_memdev(struct cxl_memdev_ops *ops) during pci_probe() using Dan's Infra.

I will use this new infra for region auto-assembling and share the v4 series shortly.


Regards,
Neeraj