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Message-ID: <c53c4b89-45a9-a5e0-c162-43dc0a6e8ed6@intel.com>
Date: Wed, 28 Sep 2022 08:45:02 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Adam Manzanares <a.manzanares@...sung.com>,
"alison.schofield@...el.com" <alison.schofield@...el.com>,
"vishal.l.verma@...el.com" <vishal.l.verma@...el.com>,
"ira.weiny@...el.com" <ira.weiny@...el.com>,
"bwidawsk@...nel.org" <bwidawsk@...nel.org>,
"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
"dave@...olabs.net" <dave@...olabs.net>,
"Jonathan.Cameron@...wei.com" <Jonathan.Cameron@...wei.com>
Cc: "linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] cxl: Replace HDM decoder granularity magic numbers
On 8/29/2022 3:03 PM, Adam Manzanares wrote:
> When reviewing the CFMWS parsing code that deals with the HDM decoders,
> I noticed a couple of magic numbers. This commit replaces these magic numbers
> with constants defined by the CXL 3.0 specification.
>
> v2:
> - Change references to CXL 3.0 specification (David)
> - CXL_DECODER_MAX_GRANULARITY_ORDER -> CXL_DECODER_MAX_ENCODED_IG (Dan)
>
> Signed-off-by: Adam Manzanares <a.manzanares@...sung.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
> drivers/cxl/cxl.h | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index f680450f0b16..3ab81ad9d2e5 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -61,6 +61,10 @@
> #define CXL_HDM_DECODER0_SKIP_LOW(i) CXL_HDM_DECODER0_TL_LOW(i)
> #define CXL_HDM_DECODER0_SKIP_HIGH(i) CXL_HDM_DECODER0_TL_HIGH(i)
>
> +/* HDM decoder control register constants CXL 3.0 8.2.5.19.7 */
> +#define CXL_DECODER_MIN_GRANULARITY 256
> +#define CXL_DECODER_MAX_ENCODED_IG 6
> +
> static inline int cxl_hdm_decoder_count(u32 cap_hdr)
> {
> int val = FIELD_GET(CXL_HDM_DECODER_COUNT_MASK, cap_hdr);
> @@ -71,9 +75,9 @@ static inline int cxl_hdm_decoder_count(u32 cap_hdr)
> /* Encode defined in CXL 2.0 8.2.5.12.7 HDM Decoder Control Register */
> static inline int cxl_to_granularity(u16 ig, unsigned int *val)
> {
> - if (ig > 6)
> + if (ig > CXL_DECODER_MAX_ENCODED_IG)
> return -EINVAL;
> - *val = 256 << ig;
> + *val = CXL_DECODER_MIN_GRANULARITY << ig;
> return 0;
> }
>
> @@ -96,7 +100,7 @@ static inline int cxl_to_ways(u8 eniw, unsigned int *val)
>
> static inline int granularity_to_cxl(int g, u16 *ig)
> {
> - if (g > SZ_16K || g < 256 || !is_power_of_2(g))
> + if (g > SZ_16K || g < CXL_DECODER_MIN_GRANULARITY || !is_power_of_2(g))
> return -EINVAL;
> *ig = ilog2(g) - 8;
> return 0;
> @@ -248,7 +252,6 @@ enum cxl_decoder_type {
> */
> #define CXL_DECODER_MAX_INTERLEAVE 16
>
> -#define CXL_DECODER_MIN_GRANULARITY 256
>
> /**
> * struct cxl_decoder - Common CXL HDM Decoder Attributes
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