Commit e4db90e4 authored by Neeraj Sanjay Kale's avatar Neeraj Sanjay Kale Committed by Luiz Augusto von Dentz
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Bluetooth: btnxpuart: Resolve TX timeout error in power save stress test 



This fixes the tx timeout issue seen while running a stress test on
btnxpuart for couple of hours, such that the interval between two HCI
commands coincide with the power save timeout value of 2 seconds.

Test procedure using bash script:
<load btnxpuart.ko>
hciconfig hci0 up
//Enable Power Save feature
hcitool -i hci0 cmd 3f 23 02 00 00
while (true)
do
    hciconfig hci0 leadv
    sleep 2
    hciconfig hci0 noleadv
    sleep 2
done

Error log, after adding few more debug prints:
Bluetooth: btnxpuart_queue_skb(): 01 0A 20 01 00
Bluetooth: hci0: Set UART break: on, status=0
Bluetooth: hci0: btnxpuart_tx_wakeup() tx_work scheduled
Bluetooth: hci0: btnxpuart_tx_work() dequeue: 01 0A 20 01 00
Can't set advertise mode on hci0: Connection timed out (110)
Bluetooth: hci0: command 0x200a tx timeout

When the power save mechanism turns on UART break, and btnxpuart_tx_work()
is scheduled simultaneously, psdata->ps_state is read as PS_STATE_AWAKE,
which prevents the psdata->work from being scheduled, which is responsible
to turn OFF UART break.

This issue is fixed by adding a ps_lock mutex around UART break on/off as
well as around ps_state read/write.
btnxpuart_tx_wakeup() will now read updated ps_state value. If ps_state is
PS_STATE_SLEEP, it will first schedule psdata->work, and then it will
reschedule itself once UART break has been turned off and ps_state is
PS_STATE_AWAKE.

Tested above script for 50,000 iterations and TX timeout error was not
observed anymore.

Signed-off-by: default avatarNeeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
parent 1fb99431

drivers/bluetooth/btnxpuart.c

+21 −3
Original line number Diff line number Diff line
@@ -126,6 +126,7 @@ struct ps_data { 
	struct hci_dev *hdev;

	struct work_struct work;

	struct timer_list ps_timer;

	struct mutex ps_lock;

};



struct wakeup_cmd_payload {
@@ -317,6 +318,9 @@ static void ps_start_timer(struct btnxpuart_dev *nxpdev) 


	if (psdata->cur_psmode == PS_MODE_ENABLE)

		mod_timer(&psdata->ps_timer, jiffies + msecs_to_jiffies(psdata->h2c_ps_interval));



	if (psdata->ps_state == PS_STATE_AWAKE && psdata->ps_cmd == PS_CMD_ENTER_PS)

		cancel_work_sync(&psdata->work);

}



static void ps_cancel_timer(struct btnxpuart_dev *nxpdev)
@@ -337,6 +341,7 @@ static void ps_control(struct hci_dev *hdev, u8 ps_state) 
	    !test_bit(BTNXPUART_SERDEV_OPEN, &nxpdev->tx_state))

		return;



	mutex_lock(&psdata->ps_lock);

	switch (psdata->cur_h2c_wakeupmode) {

	case WAKEUP_METHOD_DTR:

		if (ps_state == PS_STATE_AWAKE)
@@ -350,12 +355,15 @@ static void ps_control(struct hci_dev *hdev, u8 ps_state) 
			status = serdev_device_break_ctl(nxpdev->serdev, 0);

		else

			status = serdev_device_break_ctl(nxpdev->serdev, -1);

		msleep(20); /* Allow chip to detect UART-break and enter sleep */

		bt_dev_dbg(hdev, "Set UART break: %s, status=%d",

			   str_on_off(ps_state == PS_STATE_SLEEP), status);

		break;

	}

	if (!status)

		psdata->ps_state = ps_state;

	mutex_unlock(&psdata->ps_lock);



	if (ps_state == PS_STATE_AWAKE)

		btnxpuart_tx_wakeup(nxpdev);

}
@@ -391,17 +399,25 @@ static void ps_setup(struct hci_dev *hdev) 


	psdata->hdev = hdev;

	INIT_WORK(&psdata->work, ps_work_func);

	mutex_init(&psdata->ps_lock);

	timer_setup(&psdata->ps_timer, ps_timeout_func, 0);

}



static void ps_wakeup(struct btnxpuart_dev *nxpdev)

static bool ps_wakeup(struct btnxpuart_dev *nxpdev)

{

	struct ps_data *psdata = &nxpdev->psdata;

	u8 ps_state;



	if (psdata->ps_state != PS_STATE_AWAKE) {

	mutex_lock(&psdata->ps_lock);

	ps_state = psdata->ps_state;

	mutex_unlock(&psdata->ps_lock);



	if (ps_state != PS_STATE_AWAKE) {

		psdata->ps_cmd = PS_CMD_EXIT_PS;

		schedule_work(&psdata->work);

		return true;

	}

	return false;

}



static int send_ps_cmd(struct hci_dev *hdev, void *data)
@@ -1171,7 +1187,6 @@ static struct sk_buff *nxp_dequeue(void *data) 
{

	struct btnxpuart_dev *nxpdev = (struct btnxpuart_dev *)data;



	ps_wakeup(nxpdev);

	ps_start_timer(nxpdev);

	return skb_dequeue(&nxpdev->txq);

}
@@ -1186,6 +1201,9 @@ static void btnxpuart_tx_work(struct work_struct *work) 
	struct sk_buff *skb;

	int len;



	if (ps_wakeup(nxpdev))

		return;



	while ((skb = nxp_dequeue(nxpdev))) {

		len = serdev_device_write_buf(serdev, skb->data, skb->len);

		hdev->stat.byte_tx += len;