Re: [PATCH v2] cxl: Adjust extended linear cache failure emission in cxl_acpi

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

On Fri, 3 Oct 2025 11:55:09 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> The cxl_acpi module spams "Extended linear cache calculation failed"
> when the hmat memory target is not found for a node. This is normal
> when the memory target does not contain extended linear cache
> attributes. Adjust cxl_acpi_set_cache_size() to just return 0 if error
> is returned from hmat_get_extended_linear_cache_size(). That is the
> only error returned from hmat_get_extended_linear_cache_size() as
> -ENOENT.
> 
> Also remove the check for -EOPNOTSUPP in cxl_setup_extended_linear_cache()
> since that errno is never returned by cxl_acpi_set_cache_size().
> 
> Suggeted-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Minor thing below. Either way
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> 
> ---
> v2:
> - Rename subject line to reflect new changes.
> - Further analysis of the code and determined this is the correct
>   change.
> ---
>  drivers/cxl/acpi.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index d7a5539d07d4..cc4d7bf381d3 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -353,7 +353,7 @@ static int cxl_acpi_set_cache_size(struct cxl_root_decoder *cxlrd)
>  
>  	rc = hmat_get_extended_linear_cache_size(&res, nid, &cache_size);
>  	if (rc)
> -		return rc;
> +		return 0;
>  
>  	/*
>  	 * The cache range is expected to be within the CFMWS.
> @@ -381,15 +381,13 @@ static void cxl_setup_extended_linear_cache(struct cxl_root_decoder *cxlrd)
>  	if (!rc)
>  		return;
I'd prefer a logic flip so the error is out of line.

	if (rc) {
		/*
		 * Failing to support extended linear cache region resize does not
		 * prevent the region from functioning. Only causes cxl list showing
		 * incorrect region size.
		 */
		dev_warn(cxlrd->cxlsd.cxld.dev.parent,
			 "Extended linear cache calculation failed rc:%d\n", rc);
 		cxlrd->cache_size = 0;
	}
}
>  
> -	if (rc != -EOPNOTSUPP) {
> -		/*
> -		 * Failing to support extended linear cache region resize does not
> -		 * prevent the region from functioning. Only causes cxl list showing
> -		 * incorrect region size.
> -		 */
> -		dev_warn(cxlrd->cxlsd.cxld.dev.parent,
> -			 "Extended linear cache calculation failed rc:%d\n", rc);
> -	}
> +	/*
> +	 * Failing to retrieve extended linear cache region resize does not
> +	 * prevent the region from functioning. Only causes cxl list showing
> +	 * incorrect region size.
> +	 */
> +	dev_warn(cxlrd->cxlsd.cxld.dev.parent,
> +		 "Extended linear cache retrieval failed rc:%d\n", rc);
>  
>  	/* Ignoring return code */
>  	cxlrd->cache_size = 0;
> 
> base-commit: 46037455cbb748c5e85071c95f2244e81986eb58