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Commit 7d5ca3b8 authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by John W. Linville
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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: default avatarLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 23b149c1

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

+25 −4
Original line number Original line Diff line number Diff line
@@ -236,10 +236,31 @@ static int ath_rx_prepare(struct sk_buff *skb, struct ath_desc *ds, 
	rx_status->signal = rx_status->noise + ds->ds_rxstat.rs_rssi;

	rx_status->signal = rx_status->noise + ds->ds_rxstat.rs_rssi;

	rx_status->antenna = ds->ds_rxstat.rs_antenna;

	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

	 * Theory for reporting quality:

	 * each possible mode used. */

	 *

	 * 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;

		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

	/* rssi can be more than 45 though, anything above that

	 * should be considered at 100% */

	 * should be considered at 100% */