linux-kernel - Re: [PATCH tty-next v4 2/6] serial: 8250: Use frame rate to determine timeout

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Message-ID: <Z3By2ji2aJBCuMjT@smile.fi.intel.com>
Date: Sat, 28 Dec 2024 23:51:22 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: John Ogness <john.ogness@...utronix.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>, Petr Mladek <pmladek@...e.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Esben Haabendal <esben@...nix.com>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	Rengarajan S <rengarajan.s@...rochip.com>,
	Niklas Schnelle <schnelle@...ux.ibm.com>,
	Serge Semin <fancer.lancer@...il.com>
Subject: Re: [PATCH tty-next v4 2/6] serial: 8250: Use frame rate to
 determine timeout

On Fri, Dec 27, 2024 at 11:51:18PM +0106, John Ogness wrote:
> Rather than using a hard-coded per-character Tx-timeout of 10ms,
> use the frame rate to determine a timeout value. The value is
> doubled to ensure that a timeout is only hit during unexpected
> circumstances.
> 
> Since the frame rate may not be available during early printing,
> the previous 10ms value is kept as a fallback.

...

>  	unsigned int status, tmout = 10000;
>  
> -	/* Wait up to 10ms for the character(s) to be sent. */
> +	/*
> +	 * Wait for a character to be sent. Fallback to a safe default
> +	 * timeout value if @frame_time is not available.
> +	 */

> +

Redundant blank line (esp. after addressing below).

> +	if (up->port.frame_time)
> +		tmout = up->port.frame_time * 2 / NSEC_PER_USEC;

This will be harder to maintain in case some new code will be squeezed in
between, so I propose to make it if-else.

-- 
With Best Regards,
Andy Shevchenko