linux-kernel - [PATCH 2/2] hci_qca: Reduce delay after sending baudrate request for WCN3990

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Date:   Tue, 26 Feb 2019 12:08:48 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>
Cc:     linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        Balakrishna Godavarthi <bgodavar@...eaurora.org>,
        Hemantg <hemantg@...eaurora.org>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH 2/2] hci_qca: Reduce delay after sending baudrate request for WCN3990

The current 300ms delay after a baudrate change is extremely long.
For WCM3990 it is sufficient to wait 10ms after the baudrate change
request has been sent over the wire.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 drivers/bluetooth/hci_qca.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 703e099515f24..fd018cc5605c6 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -59,8 +59,7 @@
 
 #define IBS_WAKE_RETRANS_TIMEOUT_MS	100
 #define IBS_TX_IDLE_TIMEOUT_MS		2000
-#define BAUDRATE_SETTLE_TIMEOUT_MS	300
-#define POWER_PULSE_TRANS_TIMEOUT_MS	100
+#define CMD_TRANS_TIMEOUT_MS		100
 
 /* susclk rate */
 #define SUSCLK_RATE_32KHZ	32768
@@ -964,6 +963,7 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
 {
 	struct hci_uart *hu = hci_get_drvdata(hdev);
 	struct qca_data *qca = hu->priv;
+	struct qca_serdev *qcadev;
 	struct sk_buff *skb;
 	u8 cmd[] = { 0x01, 0x48, 0xFC, 0x01, 0x00 };
 
@@ -985,11 +985,25 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
 	skb_queue_tail(&qca->txq, skb);
 	hci_uart_tx_wakeup(hu);
 
-	/* wait 300ms to change new baudrate on controller side
-	 * controller will come back after they receive this HCI command
-	 * then host can communicate with new baudrate to controller
+	qcadev = serdev_device_get_drvdata(hu->serdev);
+
+	/* Wait for the baudrate change command to be sent and
+	 * processed by the controller.
 	 */
-	msleep(BAUDRATE_SETTLE_TIMEOUT_MS);
+	if (qcadev->btsoc_type == QCA_WCN3990) {
+		while (!skb_queue_empty(&qca->txq))
+			usleep_range(100, 200);
+
+		serdev_device_wait_until_sent(hu->serdev,
+			      msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));
+
+		/* Make sure there is enough time for the BT
+		 * controller to process the baudrate change
+		*/
+		msleep(10);
+	} else {
+		msleep(300);
+	}
 
 	return 0;
 }
@@ -1005,7 +1019,7 @@ static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed)
 static int qca_send_power_pulse(struct hci_uart *hu, u8 cmd)
 {
 	int ret;
-	int timeout = msecs_to_jiffies(POWER_PULSE_TRANS_TIMEOUT_MS);
+	int timeout = msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS);
 
 	/* These power pulses are single byte command which are sent
 	 * at required baudrate to wcn3990. On wcn3990, we have an external
-- 
2.21.0.rc2.261.ga7da99ff1b-goog