ath9k_hw: fix PLL clock initialization for newer SoC

On AR934x and newer SoC devices, the layout of the AR_RTC_PLL_CONTROL
register changed. This currently breaks at least 5/10 MHz operation.
AR933x uses the old layout.

It might also have been causing other stability issues because of the
different location of the PLL_BYPASS bit which needs to be set during
PLL clock initialization.

This patch also removes more instances of hardcoded register values in
favor of properly computed ones with the PLL_BYPASS bit added.

Reported-by: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 88654e3..8be4b14 100644
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -701,6 +701,8 @@
 {
 	u32 pll;
 
+	pll = ath9k_hw_compute_pll_control(ah, chan);
+
 	if (AR_SREV_9485(ah) || AR_SREV_9565(ah)) {
 		/* program BB PLL ki and kd value, ki=0x4, kd=0x40 */
 		REG_RMW_FIELD(ah, AR_CH0_BB_DPLL2,
@@ -751,7 +753,8 @@
 		REG_RMW_FIELD(ah, AR_CH0_DDR_DPLL3,
 			      AR_CH0_DPLL3_PHASE_SHIFT, 0x1);
 
-		REG_WRITE(ah, AR_RTC_PLL_CONTROL, 0x1142c);
+		REG_WRITE(ah, AR_RTC_PLL_CONTROL,
+			  pll | AR_RTC_9300_PLL_BYPASS);
 		udelay(1000);
 
 		/* program refdiv, nint, frac to RTC register */
@@ -767,7 +770,8 @@
 	} else if (AR_SREV_9340(ah) || AR_SREV_9550(ah) || AR_SREV_9531(ah)) {
 		u32 regval, pll2_divint, pll2_divfrac, refdiv;
 
-		REG_WRITE(ah, AR_RTC_PLL_CONTROL, 0x1142c);
+		REG_WRITE(ah, AR_RTC_PLL_CONTROL,
+			  pll | AR_RTC_9300_SOC_PLL_BYPASS);
 		udelay(1000);
 
 		REG_SET_BIT(ah, AR_PHY_PLL_MODE, 0x1 << 16);
@@ -840,7 +844,6 @@
 		udelay(1000);
 	}
 
-	pll = ath9k_hw_compute_pll_control(ah, chan);
 	if (AR_SREV_9565(ah))
 		pll |= 0x40000;
 	REG_WRITE(ah, AR_RTC_PLL_CONTROL, pll);