linux-kernel - Re: [PATCH V5 11/17] cxl/region: Add devm_cxl_pmem_add

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Message-ID: <20260115181721.00002668@huawei.com>
Date: Thu, 15 Jan 2026 18:17:21 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Neeraj Kumar <s.neeraj@...sung.com>
CC: <linux-cxl@...r.kernel.org>, <nvdimm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <gost.dev@...sung.com>,
	<a.manzanares@...sung.com>, <vishak.g@...sung.com>, <neeraj.kernel@...il.com>
Subject: Re: [PATCH V5 11/17] cxl/region: Add devm_cxl_pmem_add_region() for
 pmem region creation

On Fri,  9 Jan 2026 18:14:31 +0530
Neeraj Kumar <s.neeraj@...sung.com> wrote:

> devm_cxl_pmem_add_region() is used to create cxl region based on region
> information scanned from LSA.
> 
> devm_cxl_add_region() is used to just allocate cxlr and its fields are
> filled later by userspace tool using device attributes (*_store()).
> 
> Inspiration for devm_cxl_pmem_add_region() is taken from these device
> attributes (_store*) calls. It allocates cxlr and fills information
> parsed from LSA and calls device_add(&cxlr->dev) to initiate further
> region creation porbes
> 
> Rename __create_region() to cxl_create_region(), which will be used
> in later patch to create cxl region after fetching region information
> from LSA.
You also add a couple of parameters. At very least say why here.

> 
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>

A few things inline.  

> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 26238fb5e8cf..13779aeacd8e 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c


> +static ssize_t alloc_region_dpa(struct cxl_endpoint_decoder *cxled, u64 size)
> +{
> +	int rc;
> +
> +	if (!size)
> +		return -EINVAL;
> +
> +	if (!IS_ALIGNED(size, SZ_256M))
> +		return -EINVAL;
> +
> +	rc = cxl_dpa_free(cxled);

Add a comment on why this make sense.  What already allocated dpa that we need
to clean up?

> +	if (rc)
> +		return rc;
> +
> +	return cxl_dpa_alloc(cxled, size);
> +}


> -static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
> -					  enum cxl_partition_mode mode, int id)
> +struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
> +				     enum cxl_partition_mode mode, int id,
> +				     struct cxl_pmem_region_params *pmem_params,
> +				     struct cxl_endpoint_decoder *cxled)

I'm a little dubious that the extra parameters are buried in this patch rather than
where we first need them or a separate patch that makes it clear what they are for.

>  {