Messages in this thread Patch in this message | | | Date | Mon, 22 Aug 2022 10:17:03 -0700 | From | Davidlohr Bueso <> | Subject | Re: [PATCH] cxl: Replace HDM decoder granularity magic numbers |
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On Mon, 22 Aug 2022, 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 2.0 specification.
Please use 3.0 spec :)
Actually the whole drivers/cxl/* could use updating the comments for 3.0.
>Signed-off-by: Adam Manzanares <a.manzanares@samsung.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..ba3a66b5b9cd 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 2.0 8.2.5.12.7 */
This now becomes 8.2.4.19.7.
>+#define CXL_DECODER_MIN_GRANULARITY 256 >+#define CXL_DECODER_MAX_GRANULARITY_ORDER 6
Considering there is a single user, I don't think we need to add the CXL_DECODER_MAX_GRANULARITY_ORDER. And if a new one is added it would be better to keep symmetry (bytes) and just do CXL_DECODER_MAX_GRANULARITY, but that's probably the reason why it doesn't exist in the first place.
>+ > 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_GRANULARITY_ORDER) > 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))
Looks good.
Thanks, Davidlohr
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