linux-kernel - Re: [PATCH 04/26] cxl/region: Add dynamic capacity decoder and region modes

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Message-ID: <1c7f63c5-1b7a-4f7b-9d48-4dd8b017d7de@intel.com>
Date: Wed, 27 Mar 2024 08:43:22 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: ira.weiny@...el.com, Fan Ni <fan.ni@...sung.com>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Navneet Singh <navneet.singh@...el.com>
Cc: 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-btrfs@...r.kernel.org,
 linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/26] cxl/region: Add dynamic capacity decoder and region
 modes



On 3/24/24 4:18 PM, ira.weiny@...el.com wrote:
> From: Navneet Singh <navneet.singh@...el.com>
> 
> Region mode must reflect a general dynamic capacity type which is
> associated with a specific Dynamic Capacity (DC) partitions in each
> device decoder within the region.  DC partitions are also know as DC
> regions per CXL 3.1.

This section reads somewhat awkward to me. Does this read any better?

One or more Dynamic Capacity (DC) partitions (and decoders) form a CXL software region. The region mode reflects composition of that entire software region. Decoder mode reflects a specific DC partition. DC partitions are also known as DC regions per CXL specification r3.1 but is not the same entity as CXL software regions.

DJ

> 
> Decoder mode reflects a specific DC partition.
> 
> Define the new modes to use in subsequent patches and the helper
> functions required to make the association between these new modes.
> 
> Signed-off-by: Navneet Singh <navneet.singh@...el.com>
> Co-developed-by: Ira Weiny <ira.weiny@...el.com>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
> Changes for v1
> [iweiny: split out from: Add dynamic capacity cxl region support.]
> ---
>  drivers/cxl/core/region.c |  4 ++++
>  drivers/cxl/cxl.h         | 23 +++++++++++++++++++++++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 1723d17f121e..ec3b8c6948e9 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1690,6 +1690,8 @@ static bool cxl_modes_compatible(enum cxl_region_mode rmode,
>  		return true;
>  	if (rmode == CXL_REGION_PMEM && dmode == CXL_DECODER_PMEM)
>  		return true;
> +	if (rmode == CXL_REGION_DC && cxl_decoder_mode_is_dc(dmode))
> +		return true;
>  
>  	return false;
>  }
> @@ -2824,6 +2826,8 @@ cxl_decoder_to_region_mode(enum cxl_decoder_mode mode)
>  		return CXL_REGION_RAM;
>  	case CXL_DECODER_PMEM:
>  		return CXL_REGION_PMEM;
> +	case CXL_DECODER_DC0 ... CXL_DECODER_DC7:
> +		return CXL_REGION_DC;
>  	case CXL_DECODER_MIXED:
>  	default:
>  		return CXL_REGION_MIXED;
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 9a0cce1e6fca..3b8935089c0c 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -365,6 +365,14 @@ enum cxl_decoder_mode {
>  	CXL_DECODER_NONE,
>  	CXL_DECODER_RAM,
>  	CXL_DECODER_PMEM,
> +	CXL_DECODER_DC0,
> +	CXL_DECODER_DC1,
> +	CXL_DECODER_DC2,
> +	CXL_DECODER_DC3,
> +	CXL_DECODER_DC4,
> +	CXL_DECODER_DC5,
> +	CXL_DECODER_DC6,
> +	CXL_DECODER_DC7,
>  	CXL_DECODER_MIXED,
>  	CXL_DECODER_DEAD,
>  };
> @@ -375,6 +383,14 @@ static inline const char *cxl_decoder_mode_name(enum cxl_decoder_mode mode)
>  		[CXL_DECODER_NONE] = "none",
>  		[CXL_DECODER_RAM] = "ram",
>  		[CXL_DECODER_PMEM] = "pmem",
> +		[CXL_DECODER_DC0] = "dc0",
> +		[CXL_DECODER_DC1] = "dc1",
> +		[CXL_DECODER_DC2] = "dc2",
> +		[CXL_DECODER_DC3] = "dc3",
> +		[CXL_DECODER_DC4] = "dc4",
> +		[CXL_DECODER_DC5] = "dc5",
> +		[CXL_DECODER_DC6] = "dc6",
> +		[CXL_DECODER_DC7] = "dc7",
>  		[CXL_DECODER_MIXED] = "mixed",
>  	};
>  
> @@ -383,10 +399,16 @@ static inline const char *cxl_decoder_mode_name(enum cxl_decoder_mode mode)
>  	return "mixed";
>  }
>  
> +static inline bool cxl_decoder_mode_is_dc(enum cxl_decoder_mode mode)
> +{
> +	return (mode >= CXL_DECODER_DC0 && mode <= CXL_DECODER_DC7);
> +}
> +
>  enum cxl_region_mode {
>  	CXL_REGION_NONE,
>  	CXL_REGION_RAM,
>  	CXL_REGION_PMEM,
> +	CXL_REGION_DC,
>  	CXL_REGION_MIXED,
>  };
>  
> @@ -396,6 +418,7 @@ static inline const char *cxl_region_mode_name(enum cxl_region_mode mode)
>  		[CXL_REGION_NONE] = "none",
>  		[CXL_REGION_RAM] = "ram",
>  		[CXL_REGION_PMEM] = "pmem",
> +		[CXL_REGION_DC] = "dc",
>  		[CXL_REGION_MIXED] = "mixed",
>  	};
>  
>