Re: [PATCH v1 18/31] serial: 8250: allow low-level driver to override break_ctl()

From: Andy Shevchenko

Date: Sun Nov 30 2025 - 20:55:33 EST


On Sun, Nov 30, 2025 at 12:45 PM Crescent Hsieh
<crescentcy.hsieh@xxxxxxxx> wrote:
>
> Moxa PCIe serial boards requires custom break signal transmission under
> RS485 mdoe. However, the current 8250 driver does not provide a way for

mode

> low-level driver to override this behavior.
>
> This patch introduces a break_ctl() function pointer in struct
> uart_port, allowing low-level drivers to customize the break signal
> transmission logic. If no custom implementation is provided, the default
> serial8250_do_break_ctl() function is used. This ensures that
> hardware-specific break signaling can be implemented without affecting
> standard behavior.

...

> +EXPORT_SYMBOL_GPL(serial8250_do_break_ctl);

There is another (scoped) export used in this driver, use it for this
function as well.

--
With Best Regards,
Andy Shevchenko