MU-MIMO Rx involves different interpretation of the VHT-SIG-A compared to SU-MIMO.
The incorrect interpretation led ath10k to report VHT MCS values greater than 9 which subsequently prompted mac80211 to drop such frames. This effectively broke Rx with MU-MIMO in many cases and manifested with a kernel warning in the log which looked like this: [ 14.552520] WARNING: CPU: 2 PID: 0 at net/mac80211/rx.c:3578 ieee80211_rx+0x26c/0x940 [mac80211]() [ 14.552522] Rate marked as a VHT rate but data is invalid: MCS: 10, NSS: 2 ... call trace follows ... Signed-off-by: Michal Kazior <[email protected]> --- drivers/net/wireless/ath/ath10k/htt_rx.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c index 1b7a04366256..8ba8fa9004cf 100644 --- a/drivers/net/wireless/ath/ath10k/htt_rx.c +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c @@ -643,6 +643,8 @@ struct amsdu_subframe_hdr { __be16 len; } __packed; +#define GROUP_ID_IS_SU_MIMO(x) ((x) == 0 || (x) == 63) + static void ath10k_htt_rx_h_rates(struct ath10k *ar, struct ieee80211_rx_status *status, struct htt_rx_desc *rxd) @@ -650,6 +652,7 @@ static void ath10k_htt_rx_h_rates(struct ath10k *ar, struct ieee80211_supported_band *sband; u8 cck, rate, bw, sgi, mcs, nss; u8 preamble = 0; + u8 group_id; u32 info1, info2, info3; info1 = __le32_to_cpu(rxd->ppdu_start.info1); @@ -692,10 +695,27 @@ static void ath10k_htt_rx_h_rates(struct ath10k *ar, case HTT_RX_VHT_WITH_TXBF: /* VHT-SIG-A1 in info2, VHT-SIG-A2 in info3 TODO check this */ - mcs = (info3 >> 4) & 0x0F; - nss = ((info2 >> 10) & 0x07) + 1; bw = info2 & 3; sgi = info3 & 1; + group_id = (info2 >> 4) & 0x3F; + + if (GROUP_ID_IS_SU_MIMO(group_id)) { + mcs = (info3 >> 4) & 0x0F; + nss = ((info2 >> 10) & 0x07) + 1; + } else { + /* Hardware doesn't decode VHT-SIG-B into Rx descriptor + * so it's impossible to decode MCS. Also since + * firmware consumes Group Id Management frames host + * has no knowledge regarding group/user position + * mapping so it's impossible to pick the correct Nsts + * from VHT-SIG-A1. + * + * Bandwidth and SGI are valid so report the rateinfo + * on best-effort basis. + */ + mcs = 0; + nss = 1; + } status->rate_idx = mcs; status->vht_nss = nss; -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
