linux-kernel - Re: [PATCH v9 06/19] cxl/port: Add 'dynamic_ram

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Message-ID: <aBvHlE9QgxMZrfy4@lg>
Date: Wed, 7 May 2025 13:50:28 -0700
From: Fan Ni <nifan.cxl@...il.com>
To: Ira Weiny <ira.weiny@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>, linux-cxl@...r.kernel.org,
	nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 06/19] cxl/port: Add 'dynamic_ram_a' to endpoint
 decoder mode

On Sun, Apr 13, 2025 at 05:52:14PM -0500, Ira Weiny wrote:
> Endpoints can now support a single dynamic ram partition following the
> persistent memory partition.
> 
> Expand the mode to allow a decoder to point to the first dynamic ram
> partition.
> 
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> 

Reviewed-by: Fan Ni <fan.ni@...sung.com>

> ---
> Changes:
> [iweiny: completely re-written]
> ---
>  Documentation/ABI/testing/sysfs-bus-cxl | 18 +++++++++---------
>  drivers/cxl/core/port.c                 |  4 ++++
>  2 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> index 2b59041bb410..b2754e6047ca 100644
> --- a/Documentation/ABI/testing/sysfs-bus-cxl
> +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> @@ -358,22 +358,22 @@ Description:
>  
>  
>  What:		/sys/bus/cxl/devices/decoderX.Y/mode
> -Date:		May, 2022
> -KernelVersion:	v6.0
> +Date:		May, 2022, May 2025
> +KernelVersion:	v6.0, v6.16 (dynamic_ram_a)
>  Contact:	linux-cxl@...r.kernel.org
>  Description:
>  		(RW) When a CXL decoder is of devtype "cxl_decoder_endpoint" it
>  		translates from a host physical address range, to a device
>  		local address range. Device-local address ranges are further
> -		split into a 'ram' (volatile memory) range and 'pmem'
> -		(persistent memory) range. The 'mode' attribute emits one of
> -		'ram', 'pmem', or 'none'. The 'none' indicates the decoder is
> -		not actively decoding, or no DPA allocation policy has been
> -		set.
> +		split into a 'ram' (volatile memory) range, 'pmem' (persistent
> +		memory), and 'dynamic_ram_a' (first Dynamic RAM) range. The
> +		'mode' attribute emits one of 'ram', 'pmem', 'dynamic_ram_a' or
> +		'none'. The 'none' indicates the decoder is not actively
> +		decoding, or no DPA allocation policy has been set.
>  
>  		'mode' can be written, when the decoder is in the 'disabled'
> -		state, with either 'ram' or 'pmem' to set the boundaries for the
> -		next allocation.
> +		state, with either 'ram', 'pmem', or 'dynamic_ram_a' to set the
> +		boundaries for the next allocation.
>  
>  
>  What:		/sys/bus/cxl/devices/decoderX.Y/dpa_resource
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 0fd6646c1a2e..e98605bd39b4 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -125,6 +125,7 @@ static DEVICE_ATTR_RO(name)
>  
>  CXL_DECODER_FLAG_ATTR(cap_pmem, CXL_DECODER_F_PMEM);
>  CXL_DECODER_FLAG_ATTR(cap_ram, CXL_DECODER_F_RAM);
> +CXL_DECODER_FLAG_ATTR(cap_dynamic_ram_a, CXL_DECODER_F_RAM);
>  CXL_DECODER_FLAG_ATTR(cap_type2, CXL_DECODER_F_TYPE2);
>  CXL_DECODER_FLAG_ATTR(cap_type3, CXL_DECODER_F_TYPE3);
>  CXL_DECODER_FLAG_ATTR(locked, CXL_DECODER_F_LOCK);
> @@ -219,6 +220,8 @@ static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
>  		mode = CXL_PARTMODE_PMEM;
>  	else if (sysfs_streq(buf, "ram"))
>  		mode = CXL_PARTMODE_RAM;
> +	else if (sysfs_streq(buf, "dynamic_ram_a"))
> +		mode = CXL_PARTMODE_DYNAMIC_RAM_A;
>  	else
>  		return -EINVAL;
>  
> @@ -324,6 +327,7 @@ static struct attribute_group cxl_decoder_base_attribute_group = {
>  static struct attribute *cxl_decoder_root_attrs[] = {
>  	&dev_attr_cap_pmem.attr,
>  	&dev_attr_cap_ram.attr,
> +	&dev_attr_cap_dynamic_ram_a.attr,
>  	&dev_attr_cap_type2.attr,
>  	&dev_attr_cap_type3.attr,
>  	&dev_attr_target_list.attr,
> 
> -- 
> 2.49.0
> 

-- 
Fan Ni