ath9k_htc: Enable SGI in HT20 for AR9271

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_init.c b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
index 7ec2c2e..8b202e0 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_init.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
@@ -404,6 +404,9 @@
 		       IEEE80211_HT_CAP_SGI_40 |
 		       IEEE80211_HT_CAP_DSSSCCK40;
 
+	if (priv->ah->caps.hw_caps & ATH9K_HW_CAP_SGI_20)
+		ht_info->cap |= IEEE80211_HT_CAP_SGI_20;
+
 	ht_info->ampdu_factor = IEEE80211_HT_MAX_AMPDU_64K;
 	ht_info->ampdu_density = IEEE80211_HT_MPDU_DENSITY_8;