[PATCH rtw-next v2 1/2] wifi: rtw89: Lower the timeout in rtw89_fw_read_c2h_reg() for USB

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

This read_poll_timeout_atomic() with a delay of 1 µs and a timeout of
1000000 µs can take ~250 seconds in the worst case because sending a
USB control message takes ~250 µs.

Lower the timeout to 4000 for USB in order to reduce the maximum polling
time to ~1 second.

This problem was observed with RTL8851BU while suspending to RAM with
WOWLAN enabled. The computer sat for 4 minutes with a black screen
before suspending.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
v2:
 - Lower the timeout for USB instead of increasing the delay.
---
 drivers/net/wireless/realtek/rtw89/fw.c | 9 +++++++--
 drivers/net/wireless/realtek/rtw89/fw.h | 2 ++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
index 73a4ec988d16..b774a329e7c7 100644
--- a/drivers/net/wireless/realtek/rtw89/fw.c
+++ b/drivers/net/wireless/realtek/rtw89/fw.c
@@ -6755,13 +6755,18 @@ static int rtw89_fw_read_c2h_reg(struct rtw89_dev *rtwdev,
 	const struct rtw89_chip_info *chip = rtwdev->chip;
 	struct rtw89_fw_info *fw_info = &rtwdev->fw;
 	const u32 *c2h_reg = chip->c2h_regs;
-	u32 ret;
+	u32 ret, timeout;
 	u8 i, val;
 
 	info->id = RTW89_FWCMD_C2HREG_FUNC_NULL;
 
+	if (rtwdev->hci.type == RTW89_HCI_TYPE_USB)
+		timeout = RTW89_C2H_TIMEOUT_USB;
+	else
+		timeout = RTW89_C2H_TIMEOUT;
+
 	ret = read_poll_timeout_atomic(rtw89_read8, val, val, 1,
-				       RTW89_C2H_TIMEOUT, false, rtwdev,
+				       timeout, false, rtwdev,
 				       chip->c2h_ctrl_reg);
 	if (ret) {
 		rtw89_warn(rtwdev, "c2h reg timeout\n");
diff --git a/drivers/net/wireless/realtek/rtw89/fw.h b/drivers/net/wireless/realtek/rtw89/fw.h
index 98be7e72c685..a731c242f389 100644
--- a/drivers/net/wireless/realtek/rtw89/fw.h
+++ b/drivers/net/wireless/realtek/rtw89/fw.h
@@ -115,6 +115,8 @@ struct rtw89_h2creg_sch_tx_en {
 #define RTW89_C2HREG_HDR_LEN 2
 #define RTW89_H2CREG_HDR_LEN 2
 #define RTW89_C2H_TIMEOUT 1000000
+#define RTW89_C2H_TIMEOUT_USB 4000
+
 struct rtw89_mac_c2h_info {
 	u8 id;
 	u8 content_len;
-- 
2.50.0