mac80211: minstrel: reduce minstrel_mcs_groups size

By storing a shift value for all duration values of a group, we can
reduce precision by a neglegible amount to make it fit into a u16 value.
This improves cache footprint and reduces size:

Before:
   text    data     bss     dec     hex filename
  10024     116       0   10140    279c rc80211_minstrel_ht.o

After:
   text    data     bss     dec     hex filename
   9368     116       0    9484    250c rc80211_minstrel_ht.o

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/net/mac80211/rc80211_minstrel_ht.h b/net/mac80211/rc80211_minstrel_ht.h
index ad17df10a947..26b7a3244b47 100644
--- a/net/mac80211/rc80211_minstrel_ht.h
+++ b/net/mac80211/rc80211_minstrel_ht.h
@@ -33,9 +33,10 @@
 #define MCS_GROUP_RATES		10
 
 struct mcs_group {
-	u32 flags;
-	unsigned int streams;
-	unsigned int duration[MCS_GROUP_RATES];
+	u16 flags;
+	u8 streams;
+	u8 shift;
+	u16 duration[MCS_GROUP_RATES];
 };
 
 extern const struct mcs_group minstrel_mcs_groups[];