[PATCH v2 1/3] Bluetooth: hci_qca: use wait_until_sent() for power pulses

[Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>]

wcn3990 requires a power pulse to turn ON/OFF along with
regulators. Sometimes we are observing the power pulses are sent
out with some time delay, due to queuing these commands. This is
causing synchronization issues with chip, which intern delay the
chip setup or may end up with communication issues.

Signed-off-by: Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>
---
v2: 
  * Updated function qca_send_power_pulse()
  * addressed reviewer comments.

v1:
 * initial patch

---
 drivers/bluetooth/hci_qca.c | 37 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index f036c8f98ea3..f5dd323c1967 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1013,11 +1013,9 @@ static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed)
 		hci_uart_set_baudrate(hu, speed);
 }
 
-static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd)
+static int qca_send_power_pulse(struct hci_uart *hu, u8 cmd)
 {
-	struct hci_uart *hu = hci_get_drvdata(hdev);
-	struct qca_data *qca = hu->priv;
-	struct sk_buff *skb;
+	int ret;
 
 	/* These power pulses are single byte command which are sent
 	 * at required baudrate to wcn3990. On wcn3990, we have an external
@@ -1029,19 +1027,16 @@ static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd)
 	 * save power. Disabling hardware flow control is mandatory while
 	 * sending power pulses to SoC.
 	 */
-	bt_dev_dbg(hdev, "sending power pulse %02x to SoC", cmd);
-
-	skb = bt_skb_alloc(sizeof(cmd), GFP_KERNEL);
-	if (!skb)
-		return -ENOMEM;
-
+	bt_dev_dbg(hu->hdev, "sending power pulse %02x to SoC", cmd);
 	hci_uart_set_flow_control(hu, true);
+	ret = serdev_device_write(hu->serdev, &cmd, sizeof(cmd), 0);
+	if (ret < 0) {
+		bt_dev_err(hu->hdev, "failed to send power pulse %02x to SoC",
+			   cmd);
+		return ret;
+	}
 
-	skb_put_u8(skb, cmd);
-	hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
-
-	skb_queue_tail(&qca->txq, skb);
-	hci_uart_tx_wakeup(hu);
+	serdev_device_wait_until_sent(hu->serdev, 0);
 
 	/* Wait for 100 uS for SoC to settle down */
 	usleep_range(100, 200);
@@ -1116,7 +1111,6 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
 
 static int qca_wcn3990_init(struct hci_uart *hu)
 {
-	struct hci_dev *hdev = hu->hdev;
 	struct qca_serdev *qcadev;
 	int ret;
 
@@ -1139,12 +1133,12 @@ static int qca_wcn3990_init(struct hci_uart *hu)
 
 	/* Forcefully enable wcn3990 to enter in to boot mode. */
 	host_set_baudrate(hu, 2400);
-	ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWEROFF_PULSE);
+	ret = qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE);
 	if (ret)
 		return ret;
 
 	qca_set_speed(hu, QCA_INIT_SPEED);
-	ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWERON_PULSE);
+	ret = qca_send_power_pulse(hu, QCA_WCN3990_POWERON_PULSE);
 	if (ret)
 		return ret;
 
@@ -1274,13 +1268,8 @@ static const struct qca_vreg_data qca_soc_data = {
 
 static void qca_power_shutdown(struct hci_uart *hu)
 {
-	struct serdev_device *serdev = hu->serdev;
-	unsigned char cmd = QCA_WCN3990_POWEROFF_PULSE;
-
 	host_set_baudrate(hu, 2400);
-	hci_uart_set_flow_control(hu, true);
-	serdev_device_write_buf(serdev, &cmd, sizeof(cmd));
-	hci_uart_set_flow_control(hu, false);
+	qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE);
 	qca_power_setup(hu, false);
 }
 
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