linux-kernel - Re: [PATCH RFC v2 04/18] cxl/region: Add Dynamic Capacity decoder and region modes

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Date:   Tue, 29 Aug 2023 15:39:42 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ira Weiny <ira.weiny@...el.com>
CC:     Dan Williams <dan.j.williams@...el.com>,
        Navneet Singh <navneet.singh@...el.com>,
        Fan Ni <fan.ni@...sung.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Dave Jiang <dave.jiang@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC v2 04/18] cxl/region: Add Dynamic Capacity decoder
 and region modes

On Mon, 28 Aug 2023 22:20:55 -0700
Ira Weiny <ira.weiny@...el.com> wrote:

> Both regions and decoders will need a new mode to reflect the new type
> of partition they are targeting on a device.  Regions reflect a dynamic
> capacity type which may point to different Dynamic Capacity (DC)
> Regions.  Decoder mode reflects a specific DC Region.
> 
> Define the new modes to use in subsequent patches and the helper
> functions associated with them.
> 
> Co-developed-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Navneet Singh <navneet.singh@...el.com>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>

Looks fine, though I'll be interested to see how it is used in later patches
as DC region does feel somewhat separate from the other types.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> 
> ---
> Changes for v2:
> [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 75041903b72c..69af1354bc5b 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1772,6 +1772,8 @@ 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;
>  }
> @@ -2912,6 +2914,8 @@ cxl_decoder_to_region_mode(enum cxl_decoder_mode mode)
>  		return CXL_REGION_PMEM;
>  	case CXL_DECODER_DEAD:
>  		return CXL_REGION_DEAD;
> +	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 ed282dcd5cf5..d41f3f14fbe3 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -356,6 +356,14 @@ 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,
>  };
> @@ -366,6 +374,14 @@ 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",
>  	};
>  
> @@ -374,10 +390,16 @@ 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,
>  	CXL_REGION_DEAD,
>  };
> @@ -388,6 +410,7 @@ 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",
>  	};
>  
>