netdev - Re: [PATCH v18 11/20] cxl: Define a driver interface for DPA allocation

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Message-ID: <0a95bc03-883c-4c84-8131-7a09cdb90be2@amd.com>
Date: Mon, 22 Sep 2025 16:09:28 -0500
From: "Cheatham, Benjamin" <benjamin.cheatham@....com>
To: <alejandro.lucero-palau@....com>
CC: <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 v18 11/20] cxl: Define a driver interface for DPA
 allocation

On 9/18/2025 4:17 AM, alejandro.lucero-palau@....com wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> Region creation involves finding available DPA (device-physical-address)
> capacity to map into HPA (host-physical-address) space.
> 
> In order to support CXL Type2 devices, define an API, cxl_request_dpa(),
> that tries to allocate the DPA memory the driver requires to operate.The
> memory requested should not be bigger than the max available HPA obtained
> previously with cxl_get_hpa_freespace().
> 
> Based on https://lore.kernel.org/linux-cxl/168592158743.1948938.7622563891193802610.stgit@dwillia2-xfh.jf.intel.com/
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> ---
>  drivers/cxl/core/hdm.c | 83 ++++++++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxl.h      |  1 +
>  include/cxl/cxl.h      |  5 +++
>  3 files changed, 89 insertions(+)
> 
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index e9e1d555cec6..d1b1d8ab348a 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -3,6 +3,7 @@
>  #include <linux/seq_file.h>
>  #include <linux/device.h>
>  #include <linux/delay.h>
> +#include <cxl/cxl.h>
>  
>  #include "cxlmem.h"
>  #include "core.h"
> @@ -556,6 +557,13 @@ bool cxl_resource_contains_addr(const struct resource *res, const resource_size_
>  	return resource_contains(res, &_addr);
>  }
>  
> +/**
> + * cxl_dpa_free - release DPA (Device Physical Address)
> + *
> + * @cxled: endpoint decoder linked to the DPA
> + *
> + * Returns 0 or error.
> + */

Don't think you need this comment; it's not adding anything you can't get by just looking
at the function header.