wifi: rtw89: tweak H2C TX waiting function for SER

Some specific H2C (host to chip command) needs waiting until FW ACK by
C2H (chip to host event). However, during SER (system error recovery),
most interrupts are disabled, so we can't receive C2H immediately. It
causes this kind of H2C TX waits will always time out during SER.

To save time spent by SER, we don't do these redundant waits. And, to
make a difference from -ETIMEDOUT in other cases, we make the function
return 1 for SER case. When some H2C callers really catch `ret == 1` at
runtime, they can determine whether it's reasonable or not, and consider
how to resolve their flow if needed.
Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230516082441.11154-3-pkshih@realtek.com

drivers/net/wireless/realtek/rtw89/core.h

@@ -3505,6 +3505,7 @@ enum rtw89_flags {
 	RTW89_FLAG_LOW_POWER_MODE,
 	RTW89_FLAG_INACTIVE_PS,
 	RTW89_FLAG_CRASH_SIMULATING,
+	RTW89_FLAG_SER_HANDLING,
 	RTW89_FLAG_WOWLAN,
 	RTW89_FLAG_FORBIDDEN_TRACK_WROK,
 	RTW89_FLAG_CHANGING_INTERFACE,

drivers/net/wireless/realtek/rtw89/fw.c

@@ -3792,6 +3792,11 @@ int rtw89_fw_wow_cam_update(struct rtw89_dev *rtwdev,
 	return ret;
 }
 
+/* Return < 0, if failures happen during waiting for the condition.
+ * Return 0, when waiting for the condition succeeds.
+ * Return > 0, if the wait is considered unreachable due to driver/FW design,
+ * where 1 means during SER.
+ */
 static int rtw89_h2c_tx_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *skb,
 				 struct rtw89_wait_info *wait, unsigned int cond)
 {
@@ -3804,6 +3809,9 @@ static int rtw89_h2c_tx_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *skb,
 		return -EBUSY;
 	}
 
+	if (test_bit(RTW89_FLAG_SER_HANDLING, rtwdev->flags))
+		return 1;
+
 	return rtw89_wait_for_cond(wait, cond);
 }
 

drivers/net/wireless/realtek/rtw89/ser.c

@@ -409,6 +409,7 @@ static void ser_idle_st_hdl(struct rtw89_ser *ser, u8 evt)
 	switch (evt) {
 	case SER_EV_STATE_IN:
 		rtw89_hci_recovery_complete(rtwdev);
+		clear_bit(RTW89_FLAG_SER_HANDLING, rtwdev->flags);
 		clear_bit(RTW89_FLAG_CRASH_SIMULATING, rtwdev->flags);
 		break;
 	case SER_EV_L1_RESET_PREPARE:
@@ -421,6 +422,7 @@ static void ser_idle_st_hdl(struct rtw89_ser *ser, u8 evt)
 		ser_state_goto(ser, SER_L2_RESET_ST);
 		break;
 	case SER_EV_STATE_OUT:
+		set_bit(RTW89_FLAG_SER_HANDLING, rtwdev->flags);
 		rtw89_hci_recovery_start(rtwdev);
 		break;
 	default: