On Fri, 2018-08-17 at 14:21 -0700, Danek Duvall wrote: > The mac80211_hwsim driver puts this in its VHT capabilities info field: > > IEEE80211_VHT_CAP_RXSTBC_1 | > IEEE80211_VHT_CAP_RXSTBC_2 | > IEEE80211_VHT_CAP_RXSTBC_3 | > IEEE80211_VHT_CAP_RXSTBC_4 Uh, yeah, that's garbage. > and I don't understand what that's supposed to mean. According to > 802.11-2016, the three-bit field isn't a series of boolean values, but a > single numerical value in its three bits, where the value is the maximum > number of STBC streams, and the maximum defined value is 4. Yeah ... > But the way that the code treats it, we end up with a value of 7. Indeed. > There seems to be a similar issue in mac80211/main.c, in the definition of > mac80211_vht_capa_mod_mask. I guess this one is sort of fine - you can override here and the 7 is actually the right result, but we should put there IEEE80211_VHT_CAP_RXSTBC_MASK. > Is that a bug in the code, or a misunderstanding on my part? No other > (in-tree) drivers use any of the macros other than _1, so I don't have any > other references for how the other values might be used. It's a bug. I think it should be two changes - one, in hwsim, to just set _4 (it's fake anyway), and in mac80211/main.c to use IEEE80211_VHT_CAP_RXSTBC_MASK instead of the four values ORed together. Want to prepare such patches? Otherwise I can too. johannes
