ath9k: add calibration timeout for AR9002

ADC & I/Q calibrations could take infinite time to comple, since they
depend on received frames. In particular the I/Q mismatch calibration
requires receiving of OFDM frames for completion. But in the 2.4GHz
band, a station could receive only CCK frames for a very long time.

And while we wait for the completion of one of the mentioned
calibrations, the NF calibration is blocked. Moreover, in some
environments, I/Q calibration is unable to complete until a correct
noise calibration will be performed due to AGC behaviour.

In order to avoid delaying NF calibration on forever, limit the maximum
duration of ADCs & I/Q calibrations. If the calibration is not completed
within the maximum time, it will be interrupted and a next calibration
will be performed. The code that selects the next calibration has been
reworked to the loop so incompleted calibration will be respinned later.

А maximum calibration time of 30 seconds was selected to give the
calibration enough time to complete and to not interfere with the long
(NF) calibration.

Run tested with AR9220.
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200424004923.17129-7-ryazanov.s.a@gmail.com

drivers/net/wireless/ath/ath9k/ar9002_calib.c

@@ -19,6 +19,8 @@
 #include "ar9002_phy.h"
 
 #define AR9285_CLCAL_REDO_THRESH    1
+/* AGC & I/Q calibrations time limit, ms */
+#define AR9002_CAL_MAX_TIME		30000
 
 enum ar9002_cal_types {
 	ADC_GAIN_CAL = BIT(0),
@@ -104,6 +106,14 @@ static bool ar9002_hw_per_calibration(struct ath_hw *ah,
 			} else {
 				ar9002_hw_setup_calibration(ah, currCal);
 			}
+		} else if (time_after(jiffies, ah->cal_start_time +
+				      msecs_to_jiffies(AR9002_CAL_MAX_TIME))) {
+			REG_CLR_BIT(ah, AR_PHY_TIMING_CTRL4(0),
+				    AR_PHY_TIMING_CTRL4_DO_CAL);
+			ath_dbg(ath9k_hw_common(ah), CALIBRATE,
+				"calibration timeout\n");
+			currCal->calState = CAL_WAITING;	/* Try later */
+			iscaldone = true;
 		}
 	} else if (!(caldata->CalValid & currCal->calData->calType)) {
 		ath9k_hw_reset_calibration(ah, currCal);
@@ -679,8 +689,19 @@ static int ar9002_hw_calibrate(struct ath_hw *ah, struct ath9k_channel *chan,
 		if (!ar9002_hw_per_calibration(ah, chan, rxchainmask, currCal))
 			return 0;
 
-		ah->cal_list_curr = currCal = currCal->calNext;
-		percal_pending = currCal->calState == CAL_WAITING;
+		/* Looking for next waiting calibration if any */
+		for (currCal = currCal->calNext; currCal != ah->cal_list_curr;
+		     currCal = currCal->calNext) {
+			if (currCal->calState == CAL_WAITING)
+				break;
+		}
+		if (currCal->calState == CAL_WAITING) {
+			percal_pending = true;
+			ah->cal_list_curr = currCal;
+		} else {
+			percal_pending = false;
+			ah->cal_list_curr = ah->cal_list;
+		}
 	}
 
 	/* Do not start a next calibration if the longcal is in action */

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

@@ -176,6 +176,7 @@ void ath9k_hw_reset_calibration(struct ath_hw *ah,
 
 	ath9k_hw_setup_calibration(ah, currCal);
 
+	ah->cal_start_time = jiffies;
 	currCal->calState = CAL_RUNNING;
 
 	for (i = 0; i < AR5416_MAX_CHAINS; i++) {

drivers/net/wireless/ath/ath9k/hw.h

@@ -834,6 +834,7 @@ struct ath_hw {
 
 	/* Calibration */
 	u32 supp_cals;
+	unsigned long cal_start_time;
 	struct ath9k_cal_list iq_caldata;
 	struct ath9k_cal_list adcgain_caldata;
 	struct ath9k_cal_list adcdc_caldata;