Re: [PATCH tty-next v5 2/6] serial: 8250: Use frame time to determine timeout

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Jan 07, 2025 at 10:32:58PM +0106, John Ogness wrote:
> Rather than using a hard-coded per-character Tx-timeout of 10ms,
> use the frame time to determine a timeout value. The value is
> doubled to ensure that a timeout is only hit during unexpected
> circumstances.
> 
> Since the frame time may not be available during early printing,
> the previous 10ms value is kept as a fallback.

...

> +	/*
> +	 * Wait for a character to be sent. Fallback to a safe default
> +	 * timeout value if @frame_time is not available.
> +	 */
> +	if (up->port.frame_time)
> +		tmout = up->port.frame_time * 2 / NSEC_PER_USEC;
> +	else
> +		tmout = 10000;

I would use it in a form of

		tmout = 10 * USEC_PER_MSEC;

This will give a hint of the real unit (10 ms in us).

-- 
With Best Regards,
Andy Shevchenko