[PATCH v3 4/5] wifi: ath9k: batch the read-modify-writes of a channel change

["Nerijus Bendžiūnas" <nerijus.bendziunas@gmail.com>]

ar5008_hw_set_delta_slope() and ath9k_hw_start_nfcal() each issue a run
of read-modify-writes with no register read in between. Both run on
every channel change, and on the USB devices each REG_RMW is a separate
WMI command.

Wrap both runs in ENABLE_REG_RMW_BUFFER() and REG_RMW_BUFFER_FLUSH() so
the USB transport sends each run as one command. PCI does not install
the buffer callbacks, so the macros do nothing there and the writes are
issued as before. The same holds for USB devices with firmware older
than 1.4, which have no WMI_REG_RMW_CMDID. ar5008_hw_set_delta_slope()
is the AR5008 and AR9002 callback; AR9003 has its own and is not
touched.

Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Nerijus Bendžiūnas <nerijus.bendziunas@gmail.com>
---
 drivers/net/wireless/ath/ath9k/ar5008_phy.c | 2 ++
 drivers/net/wireless/ath/ath9k/calib.c      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/ar5008_phy.c b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
index 7a45f5f62826..af05dcf95a61 100644
--- a/drivers/net/wireless/ath/ath9k/ar5008_phy.c
+++ b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
@@ -868,6 +868,7 @@ static void ar5008_hw_set_delta_slope(struct ath_hw *ah,
 	ath9k_hw_get_delta_slope_vals(ah, coef_scaled, &ds_coef_man,
 				      &ds_coef_exp);
 
+	ENABLE_REG_RMW_BUFFER(ah);
 	REG_RMW_FIELD(ah, AR_PHY_TIMING3,
 		      AR_PHY_TIMING3_DSC_MAN, ds_coef_man);
 	REG_RMW_FIELD(ah, AR_PHY_TIMING3,
@@ -882,6 +883,7 @@ static void ar5008_hw_set_delta_slope(struct ath_hw *ah,
 		      AR_PHY_HALFGI_DSC_MAN, ds_coef_man);
 	REG_RMW_FIELD(ah, AR_PHY_HALFGI,
 		      AR_PHY_HALFGI_DSC_EXP, ds_coef_exp);
+	REG_RMW_BUFFER_FLUSH(ah);
 }
 
 static bool ar5008_hw_rfbus_req(struct ath_hw *ah)
diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
index b4ab85bd7895..73c63ab32d53 100644
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -224,6 +224,7 @@ void ath9k_hw_start_nfcal(struct ath_hw *ah, bool update)
 	if (ah->caldata)
 		set_bit(NFCAL_PENDING, &ah->caldata->cal_flags);
 
+	ENABLE_REG_RMW_BUFFER(ah);
 	REG_SET_BIT(ah, AR_PHY_AGC_CONTROL(ah),
 		    AR_PHY_AGC_CONTROL_ENABLE_NF);
 
@@ -235,6 +236,7 @@ void ath9k_hw_start_nfcal(struct ath_hw *ah, bool update)
 		    AR_PHY_AGC_CONTROL_NO_UPDATE_NF);
 
 	REG_SET_BIT(ah, AR_PHY_AGC_CONTROL(ah), AR_PHY_AGC_CONTROL_NF);
+	REG_RMW_BUFFER_FLUSH(ah);
 }
 
 int ath9k_hw_loadnf(struct ath_hw *ah, struct ath9k_channel *chan)
-- 
2.55.0