ath9k: feed only active spectral / dfs-detector

Radar pulse and spectral scan reports are provided by the HW
with the ATH9K_RXERR_PHY flag set. Those are forwarded to
the dfs-detector and spectral module for further processing.

For some older chips, the pre-conditions checked in those
modules are ambiguous, since ATH9K_PHYERR_RADAR is used to
tag both types. As a result, spectral frames are fed into
the dfs-detector and vice versa.

This could lead to a false radar detection on a non-DFS
channel (which is uncritical), but more relevant it causes
useless CPU load for processing invalid frames.

This commit ensures that the dfs-detector and spectral
collector are only fed when they are active.

Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath9k/recv.c

@@ -867,10 +867,21 @@ static int ath9k_rx_skb_preprocess(struct ath_softc *sc,
 	 * can be dropped.
 	 */
 	if (rx_stats->rs_status & ATH9K_RXERR_PHY) {
-		ath9k_dfs_process_phyerr(sc, hdr, rx_stats, rx_status->mactime);
-		if (ath_cmn_process_fft(&sc->spec_priv, hdr, rx_stats, rx_status->mactime))
+		/*
+		 * DFS and spectral are mutually exclusive
+		 *
+		 * Since some chips use PHYERR_RADAR as indication for both, we
+		 * need to double check which feature is enabled to prevent
+		 * feeding spectral or dfs-detector with wrong frames.
+		 */
+		if (hw->conf.radar_enabled) {
+			ath9k_dfs_process_phyerr(sc, hdr, rx_stats,
+						 rx_status->mactime);
+		} else if (sc->spec_priv.spectral_mode != SPECTRAL_DISABLED &&
+			   ath_cmn_process_fft(&sc->spec_priv, hdr, rx_stats,
+					       rx_status->mactime)) {
 			RX_STAT_INC(rx_spectral);
-
+		}
 		return -EINVAL;
 	}