netdev - Re: [PATCH v23 16/22] cxl: Make region type based on endpoint type

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Message-ID: <474e80b2-fac9-496f-b788-276213a4e8df@amd.com>
Date: Wed, 11 Feb 2026 16:11:12 -0600
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: <alejandro.lucero-palau@....com>
CC: Alejandro Lucero <alucerop@....com>, Zhi Wang <zhiw@...dia.com>, "Jonathan
 Cameron" <Jonathan.Cameron@...wei.com>, Alison Schofield
	<alison.schofield@...el.com>, Davidlohr Bueso <daves@...olabs.net>,
	<linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
	<dan.j.williams@...el.com>, <edward.cree@....com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<dave.jiang@...el.com>
Subject: Re: [PATCH v23 16/22] cxl: Make region type based on endpoint type

On 2/1/2026 9:54 AM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> Current code is expecting Type3 or CXL_DECODER_HOSTONLYMEM devices only.
> Support for Type2 implies region type needs to be based on the endpoint
> type HDM-D[B] instead.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> Reviewed-by: Zhi Wang <zhiw@...dia.com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>
> Reviewed-by: Alison Schofield <alison.schofield@...el.com>
> Reviewed-by: Davidlohr Bueso <daves@...olabs.net>
> ---
>  drivers/cxl/core/region.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index bdefd088f5f1..f53b2e9fd9e6 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2833,7 +2833,8 @@ static ssize_t create_ram_region_show(struct device *dev,
>  }
>  
>  static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
> -					  enum cxl_partition_mode mode, int id)
> +					  enum cxl_partition_mode mode, int id,
> +					  enum cxl_decoder_type target_type)
>  {
>  	int rc;
>  
> @@ -2855,7 +2856,7 @@ static struct cxl_region *__create_region(struct cxl_root_decoder *cxlrd,
>  		return ERR_PTR(-EBUSY);
>  	}
>  
> -	return devm_cxl_add_region(cxlrd, id, mode, CXL_DECODER_HOSTONLYMEM);
> +	return devm_cxl_add_region(cxlrd, id, mode, target_type);
>  }
>  
>  static ssize_t create_region_store(struct device *dev, const char *buf,
> @@ -2869,7 +2870,7 @@ static ssize_t create_region_store(struct device *dev, const char *buf,
>  	if (rc != 1)
>  		return -EINVAL;
>  
> -	cxlr = __create_region(cxlrd, mode, id);
> +	cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM);

I haven't read the ABI docs, but would it be worthwhile to update the documentation for this attribute
to mention it only makes type 3 regions? I'm flip-flopping on whether it's worth the trouble but thought
I should mention it.

Either way:
Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>

>  	if (IS_ERR(cxlr))
>  		return PTR_ERR(cxlr);
>  
> @@ -4036,7 +4037,8 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
>  
>  	do {
>  		cxlr = __create_region(cxlrd, cxlds->part[part].mode,
> -				       atomic_read(&cxlrd->region_id));
> +				       atomic_read(&cxlrd->region_id),
> +				       cxled->cxld.target_type);
>  	} while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
>  
>  	if (IS_ERR(cxlr)) {