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Bluetooth: btnxpuart: Resolve TX timeout error in power save stress test

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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: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Neeraj Sanjay Kale 2023-12-27 18:59:27 +05:30 committed by Luiz Augusto von Dentz
parent 1fb9943146
commit e4db90e4eb
1 changed files with 21 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/bluetooth/btnxpuart.c
View File

@ -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;