ath9k: differentiate quality reporting between legacy and HT configurations
We were not differentiating quality between legacy and HT
configurations. We change this to consider the differences.
New theory for reporting quality:
At a hardware RSSI of 45 you will be able to use MCS 7 reliably.
At a hardware RSSI of 45 you will be able to use MCS 15 reliably.
At a hardware RSSI of 35 you should be able use 54 Mbps reliably.
MCS 7 is the highets MCS index usable by a 1-stream device.
MCS 15 is the highest MCS index usable by a 2-stream device.
All ath9k devices are either 1-stream or 2-stream.
How many bars you see is derived from the qual reporting.
A more elaborate scheme can be used here but it requires tables
of SNR/throughput for each possible mode used. For the MCS table
you can refer to the wireless wiki:
http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n
This should fix this bug report:
http://bugzilla.kernel.org/show_bug.cgi?id=13537
Cc: Janath.Peiris@atheros.com
Cc: Matt.Smith@atheros.com
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 2b2872b..b3da81d 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -236,10 +236,31 @@
rx_status->signal = rx_status->noise + ds->ds_rxstat.rs_rssi;
rx_status->antenna = ds->ds_rxstat.rs_antenna;
- /* at 45 you will be able to use MCS 15 reliably. A more elaborate
- * scheme can be used here but it requires tables of SNR/throughput for
- * each possible mode used. */
- rx_status->qual = ds->ds_rxstat.rs_rssi * 100 / 45;
+ /*
+ * Theory for reporting quality:
+ *
+ * At a hardware RSSI of 45 you will be able to use MCS 7 reliably.
+ * At a hardware RSSI of 45 you will be able to use MCS 15 reliably.
+ * At a hardware RSSI of 35 you should be able use 54 Mbps reliably.
+ *
+ * MCS 7 is the highets MCS index usable by a 1-stream device.
+ * MCS 15 is the highest MCS index usable by a 2-stream device.
+ *
+ * All ath9k devices are either 1-stream or 2-stream.
+ *
+ * How many bars you see is derived from the qual reporting.
+ *
+ * A more elaborate scheme can be used here but it requires tables
+ * of SNR/throughput for each possible mode used. For the MCS table
+ * you can refer to the wireless wiki:
+ *
+ * http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n
+ *
+ */
+ if (conf_is_ht(&hw->conf))
+ rx_status->qual = ds->ds_rxstat.rs_rssi * 100 / 45;
+ else
+ rx_status->qual = ds->ds_rxstat.rs_rssi * 100 / 35;
/* rssi can be more than 45 though, anything above that
* should be considered at 100% */