Re: [PATCH 2/6] cxl/mem: Arrange for always-synchronous memdev attach

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Wed,  3 Dec 2025 18:21:32 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> In preparation for CXL accelerator drivers that have a hard dependency on
> CXL capability initialization, arrange for cxl_mem_probe() to always run
> synchronous with the device_add() of cxl_memdev instances. I.e.
> cxl_mem_driver registration is always complete before the first memdev
> creation event.
> 
> At present, cxl_pci does not care about the attach state of the cxl_memdev
> because all generic memory expansion functionality can be handled by the
> cxl_core. For accelerators, however, that driver needs to perform driver
> specific initialization if CXL is available, or execute a fallback to PCIe
> only operation.
> 
> This synchronous attach guarantee is also needed for Soft Reserve Recovery,
> which is an effort that needs to assert that devices have had a chance to
> attach before making a go / no-go decision on proceeding with CXL subsystem
> initialization.
> 
> By moving devm_cxl_add_memdev() to cxl_mem.ko it removes async module
> loading as one reason that a memdev may not be attached upon return from
> devm_cxl_add_memdev().
> 
> Cc: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
> Cc: Alejandro Lucero <alucerop@amd.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Seems fine to me as well. Even independent of the reasons that
drove this patch set I'm keen on the simpler mental model that synchronous
probing allows.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>