ath9k_hw: read and backup AR_WA register value even before chip reset on.

We need to read and backup AR_WA register value permanently and reading
this after the chip is awakened results in this register being zeroed out.

This seems to fix the ASPM with L1 enabled issue that we have observed.
The laptop becomes very slow and hangs mostly with ASPM L1 enabled without
this fix.

Cc: Stable Kernel <stable@kernel.org>
Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -494,6 +494,15 @@ static int __ath9k_hw_init(struct ath_hw *ah)
 
 	ath9k_hw_read_revisions(ah);
 
+	/*
+	 * Read back AR_WA into a permanent copy and set bits 14 and 17.
+	 * We need to do this to avoid RMW of this register. We cannot
+	 * read the reg when chip is asleep.
+	 */
+	ah->WARegVal = REG_READ(ah, AR_WA);
+	ah->WARegVal |= (AR_WA_D3_L1_DISABLE |
+			 AR_WA_ASPM_TIMER_BASED_DISABLE);
+
 	if (!ath9k_hw_set_reset_reg(ah, ATH9K_RESET_POWER_ON)) {
 		ath_err(common, "Couldn't reset chip\n");
 		return -EIO;
@@ -562,14 +571,6 @@ static int __ath9k_hw_init(struct ath_hw *ah)
 
 	ath9k_hw_init_mode_regs(ah);
 
-	/*
-	 * Read back AR_WA into a permanent copy and set bits 14 and 17.
-	 * We need to do this to avoid RMW of this register. We cannot
-	 * read the reg when chip is asleep.
-	 */
-	ah->WARegVal = REG_READ(ah, AR_WA);
-	ah->WARegVal |= (AR_WA_D3_L1_DISABLE |
-			 AR_WA_ASPM_TIMER_BASED_DISABLE);
 
 	if (ah->is_pciexpress)
 		ath9k_hw_configpcipowersave(ah, 0, 0);