Re: [PATCH v1 1/2] Bluetooth: btnxpuart: Add msleep() after changing the baudrate

[Paul Menzel]

Dear Neeraj,


Thank you for your patch. For the summary/title, I suggest:

Sleep 100 ms after baud rate change

Am 27.03.25 um 19:25 schrieb Neeraj Sanjay Kale:
> This adds a 100 millisec sleep after change baudrate vendor command.
>
> It is observed that when the baudrate change command changes the
> baudrate from 3000000 to 115200, any immediate HCI command returns an
> error -22 (Device Busy).

Really 3 million?

Is this happening with every change, or only decreasing the baud rate 
with the values you listed?

> Adding a small delay after the change baudrate command complete event is
> received helps fix the issue.

100 ms is not small to me. Is this issue documented in the hardware 
documentation? Are there other ways like polling, if the command succeeded?

> Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@xxxxxxx>
> ---
>   drivers/bluetooth/btnxpuart.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
> index 5091dea762a0..e26fabe8fb3d 100644
> --- a/drivers/bluetooth/btnxpuart.c
> +++ b/drivers/bluetooth/btnxpuart.c
> @@ -1238,6 +1238,8 @@ static int nxp_set_baudrate_cmd(struct hci_dev *hdev, void *data)
>   		if (*status == 0) {
>   			serdev_device_set_baudrate(nxpdev->serdev, nxpdev->new_baudrate);
>   			nxpdev->current_baudrate = nxpdev->new_baudrate;
> +			/* Allow sufficiant time for chip to switch to new baudrate */

Please add the datasheet section.
sufficient

> +			sleep(100);
>   		}
>   		bt_dev_dbg(hdev, "Set baudrate response: status=%d, baudrate=%d",
>   			   *status, nxpdev->new_baudrate);


Kind regards,

Paul