linux-kernel - [PATCH 1/3] Bluetooth: hci_ldisc: Add function to wait for characters to be sent

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Message-Id: <20190614072351.17390-2-s.hauer@pengutronix.de>
Date:   Fri, 14 Jun 2019 09:23:49 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     linux-bluetooth@...r.kernel.org
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-kernel@...r.kernel.org,
        Loic Poulain <loic.poulain@...el.com>, kernel@...gutronix.de,
        Sascha Hauer <s.hauer@...gutronix.de>
Subject: [PATCH 1/3] Bluetooth: hci_ldisc: Add function to wait for characters to be sent

The hci UART line discipline sends its characters in a workqueue. Some
devices like the Marvell Bluetooth chips need to make sure that all
queued characters are sent before switching the baudrate. This adds
a function to synchronize with the workqueue.

Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
 drivers/bluetooth/hci_ldisc.c | 8 ++++++++
 drivers/bluetooth/hci_uart.h  | 1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index c84f985f348d..8950e07889fe 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -178,6 +178,7 @@ static void hci_uart_write_work(struct work_struct *work)
 		goto restart;
 
 	clear_bit(HCI_UART_SENDING, &hu->tx_state);
+	wake_up_bit(&hu->tx_state, HCI_UART_SENDING);
 }
 
 void hci_uart_init_work(struct work_struct *work)
@@ -213,6 +214,13 @@ int hci_uart_init_ready(struct hci_uart *hu)
 	return 0;
 }
 
+int hci_uart_wait_until_sent(struct hci_uart *hu)
+{
+	return wait_on_bit_timeout(&hu->tx_state, HCI_UART_SENDING,
+				   TASK_INTERRUPTIBLE,
+				   msecs_to_jiffies(2000));
+}
+
 /* ------- Interface to HCI layer ------ */
 /* Reset device */
 static int hci_uart_flush(struct hci_dev *hdev)
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index d8cf005e3c5d..f11af3912ce6 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -100,6 +100,7 @@ int hci_uart_register_device(struct hci_uart *hu, const struct hci_uart_proto *p
 void hci_uart_unregister_device(struct hci_uart *hu);
 
 int hci_uart_tx_wakeup(struct hci_uart *hu);
+int hci_uart_wait_until_sent(struct hci_uart *hu);
 int hci_uart_init_ready(struct hci_uart *hu);
 void hci_uart_init_work(struct work_struct *work);
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
-- 
2.20.1