ath5k: Calibration re-work

Noise floor calibration does not interfere with traffic and should run more
often as part of our "short calibration". The full calibration is not the
noise floor calibration but the AGC + Gain_F (on RF5111 and RF5112) calibration
and should run less often because it does interfere with traffic.

So

Short calibration -> I/Q & NF Calibration
Long calibration -> Short + AGC + Gain_F

This patch was for some time on my pub/ dir on www.kernel.org and has been tested
by a few people and me. I think it's O.K. to go in.

I also changed ah_calibration to ah_iq_cal_needed to make more sense.

v2 Use a workqueue instead of a tasklet for calibration

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 62 insertions, 20 deletions

diff --git a/drivers/net/wireless/ath/ath5k/phy.c b/drivers/net/wireless/ath/ath5k/phy.c
index 01cb72de44cb..ca4241d2a774 100644
--- a/drivers/net/wireless/ath/ath5k/phy.c
+++ b/drivers/net/wireless/ath/ath5k/phy.c
@@ -338,9 +338,6 @@ static void ath5k_hw_wait_for_synth(struct ath5k_hw *ah,
  * And this is the MadWiFi bug entry related to the above
  * http://madwifi-project.org/ticket/1659
  * with various measurements and diagrams
- *
- * TODO: Deal with power drops due to probes by setting an appropriate
- * tx power on the probe packets ! Make this part of the calibration process.
  */
 
 /* Initialize ah_gain during attach */
@@ -372,10 +369,9 @@ int ath5k_hw_rfgain_opt_init(struct ath5k_hw *ah)
  * tx power and a Peak to Average Power Detector (PAPD) will try
  * to measure the gain.
  *
- * XXX:  How about forcing a tx packet (bypassing PCU arbitrator etc)
+ * TODO: Force a tx packet (bypassing PCU arbitrator etc)
  * just after we enable the probe so that we don't mess with
- * standard traffic ? Maybe it's time to use sw interrupts and
- * a probe tasklet !!!
+ * standard traffic.
  */
 static void ath5k_hw_request_rfgain_probe(struct ath5k_hw *ah)
 {
@@ -575,9 +571,7 @@ done:
 /* Main callback for thermal RF gain calibration engine
  * Check for a new gain reading and schedule an adjustment
  * if needed.
- *
- * TODO: Use sw interrupt to schedule reset if gain_F needs
- * adjustment */
+ */
 enum ath5k_rfgain ath5k_hw_gainf_calibrate(struct ath5k_hw *ah)
 {
 	u32 data, type;
@@ -1390,6 +1384,8 @@ void ath5k_hw_update_noise_floor(struct ath5k_hw *ah)
 		return;
 	}
 
+	ah->ah_cal_mask |= AR5K_CALIBRATION_NF;
+
 	ee_mode = ath5k_eeprom_mode_from_channel(ah->ah_current_channel);
 
 	/* completed NF calibration, test threshold */
@@ -1434,6 +1430,8 @@ void ath5k_hw_update_noise_floor(struct ath5k_hw *ah)
 
 	ah->ah_noise_floor = nf;
 
+	ah->ah_cal_mask &= ~AR5K_CALIBRATION_NF;
+
 	ATH5K_DBG(ah, ATH5K_DEBUG_CALIBRATE,
 		"noise floor calibrated: %d\n", nf);
 }
@@ -1547,12 +1545,19 @@ ath5k_hw_rf511x_iq_calibrate(struct ath5k_hw *ah)
 	s32 iq_corr, i_coff, i_coffd, q_coff, q_coffd;
 	int i;
 
-	if (!ah->ah_calibration ||
-		ath5k_hw_reg_read(ah, AR5K_PHY_IQ) & AR5K_PHY_IQ_RUN)
-		return 0;
+	/* Skip if I/Q calibration is not needed or if it's still running */
+	if (!ah->ah_iq_cal_needed)
+		return -EINVAL;
+	else if (ath5k_hw_reg_read(ah, AR5K_PHY_IQ) & AR5K_PHY_IQ_RUN) {
+		ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_CALIBRATE,
+				"I/Q calibration still running");
+		return -EBUSY;
+	}
 
 	/* Calibration has finished, get the results and re-run */
-	/* work around empty results which can apparently happen on 5212 */
+
+	/* Work around for empty results which can apparently happen on 5212:
+	 * Read registers up to 10 times until we get both i_pr and q_pwr */
 	for (i = 0; i <= 10; i++) {
 		iq_corr = ath5k_hw_reg_read(ah, AR5K_PHY_IQRES_CAL_CORR);
 		i_pwr = ath5k_hw_reg_read(ah, AR5K_PHY_IQRES_CAL_PWR_I);
@@ -1570,9 +1575,13 @@ ath5k_hw_rf511x_iq_calibrate(struct ath5k_hw *ah)
 	else
 		q_coffd = q_pwr >> 7;
 
-	/* protect against divide by 0 and loss of sign bits */
+	/* In case i_coffd became zero, cancel calibration
+	 * not only it's too small, it'll also result a divide
+	 * by zero later on. */
 	if (i_coffd == 0 || q_coffd < 2)
-		return 0;
+		return -ECANCELED;
+
+	/* Protect against loss of sign bits */
 
 	i_coff = (-iq_corr) / i_coffd;
 	i_coff = clamp(i_coff, -32, 31); /* signed 6 bit */
@@ -1613,10 +1622,43 @@ int ath5k_hw_phy_calibrate(struct ath5k_hw *ah,
 		return ath5k_hw_rf5110_calibrate(ah, channel);
 
 	ret = ath5k_hw_rf511x_iq_calibrate(ah);
+	if (ret) {
+		ATH5K_DBG_UNLIMIT(ah, ATH5K_DEBUG_CALIBRATE,
+			"No I/Q correction performed (%uMHz)\n",
+			channel->center_freq);
+
+		/* Happens all the time if there is not much
+		 * traffic, consider it normal behaviour. */
+		ret = 0;
+	}
+
+	/* On full calibration do an AGC calibration and
+	 * request a PAPD probe for gainf calibration if
+	 * needed */
+	if (ah->ah_cal_mask & AR5K_CALIBRATION_FULL) {
+
+		AR5K_REG_ENABLE_BITS(ah, AR5K_PHY_AGCCTL,
+					AR5K_PHY_AGCCTL_CAL);
+
+		ret = ath5k_hw_register_timeout(ah, AR5K_PHY_AGCCTL,
+			AR5K_PHY_AGCCTL_CAL | AR5K_PHY_AGCCTL_NF,
+			0, false);
+		if (ret) {
+			ATH5K_ERR(ah,
+				"gain calibration timeout (%uMHz)\n",
+				channel->center_freq);
+		}
+
+		if ((ah->ah_radio == AR5K_RF5111 ||
+			ah->ah_radio == AR5K_RF5112)
+			&& (channel->hw_value != AR5K_MODE_11B))
+			ath5k_hw_request_rfgain_probe(ah);
+	}
 
-	if ((ah->ah_radio == AR5K_RF5111 || ah->ah_radio == AR5K_RF5112) &&
-	    (channel->hw_value != AR5K_MODE_11B))
-		ath5k_hw_request_rfgain_probe(ah);
+	/* Update noise floor
+	 * XXX: Only do this after AGC calibration */
+	if (!(ah->ah_cal_mask & AR5K_CALIBRATION_NF))
+		ath5k_hw_update_noise_floor(ah);
 
 	return ret;
 }
@@ -3433,9 +3475,9 @@ int ath5k_hw_phy_init(struct ath5k_hw *ah, struct ieee80211_channel *channel,
 
 	/* At the same time start I/Q calibration for QAM constellation
 	 * -no need for CCK- */
-	ah->ah_calibration = false;
+	ah->ah_iq_cal_needed = false;
 	if (!(mode == AR5K_MODE_11B)) {
-		ah->ah_calibration = true;
+		ah->ah_iq_cal_needed = true;
 		AR5K_REG_WRITE_BITS(ah, AR5K_PHY_IQ,
 				AR5K_PHY_IQ_CAL_NUM_LOG_MAX, 15);
 		AR5K_REG_ENABLE_BITS(ah, AR5K_PHY_IQ,