Hi Frédéric,
On Wed, Aug 14, 2024 at 9:07 AM Frédéric Danis
<frederic.danis@xxxxxxxxxxxxx> wrote:
>
> Starting a BCM UART controller not defined as a platform device or
> a serdev with "btattach -B /dev/ttyS1 -P bcm -S 3000000" works fine
> but the serial port remains at the init_speed, i.e. 115200.
>
> The oper_speed is only set if a device is declared in ACPI, device
> tree or as a platform device.
>
> When no registered device has been found this commit will use the
> current tty speed set by btattach as the oper_speed.
>
> Signed-off-by: Frédéric Danis <frederic.danis@xxxxxxxxxxxxx>
> ---
>
> This has been tested with 5.4 kernel only.
> Afaict there's no change in this driver which should be impacted by
> this commit in latest kernel.
>
> drivers/bluetooth/hci_bcm.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
> index 89d4c2224546..57cacf63ae12 100644
> --- a/drivers/bluetooth/hci_bcm.c
> +++ b/drivers/bluetooth/hci_bcm.c
> @@ -508,6 +508,11 @@ static int bcm_open(struct hci_uart *hu)
>
> if (err)
> goto err_unset_hu;
> + } else {
> + /* This is not a serdev or platform device, it should have been started by
> + * btattach, in this case use the tty speed set by btattach as oper_speed
> + */
> + hu->oper_speed = hu->tty->termios.c_ospeed;
> }
While Im fine with the general idea of derive the speed from the tty
what Im not sure where it should be done since doing this on the
driver may duplicate the logic if we later found there is a better
place to do it.
Looks at hci_uart.c it seems like we could actually register a set_termios:
* @set_termios: [TTY] ``void ()(struct tty_struct *tty, const struct
ktermios *old)``
*
* This function notifies the line discpline that a change has been made
* to the termios structure.
*
* Optional.
So I assume when the user changes the speed the above callback gets
called and we could then reflect the changes to the oper_speed, or
perhaps the real problem was that hci_uart_set_baudrate was not
called?
> mutex_unlock(&bcm_device_lock);
> --
> 2.34.1
>
>
--
Luiz Augusto von Dentz
