linux-kernel - Re: [PATCH] SC26XX: New serial driver for SC2681 uarts

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Date:	Tue, 4 Dec 2007 19:27:38 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	tsbogend@...ha.franken.de (Thomas Bogendoerfer)
Cc:	linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org,
	Andy Whitcroft <apw@...dowen.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] SC26XX: New serial driver for SC2681 uarts

On Wed, 5 Dec 2007 00:41:12 +0100 tsbogend@...ha.franken.de (Thomas Bogendoerfer) wrote:

> On Mon, Dec 03, 2007 at 03:53:17PM -0800, Andrew Morton wrote:
> > On Sun,  2 Dec 2007 20:43:46 +0100 (CET)
> > Thomas Bogendoerfer <tsbogend@...ha.franken.de> wrote:
> > 
> > > New serial driver for SC2681/SC2691 uarts. Older SNI RM400 machines are
> > > using these chips for onboard serial ports.
> > > 
> > 
> > Little things...
> 
> here is an updated version.
> 
> Changes:
>    - use container_of
>    - remove not needed locking
>    - remove inlines
>    - fix macros with double argument reference
> 
> Thomas.
> --
> 
> New serial driver for SC2681/SC2691 uarts. Older SNI RM400 machines are
> using these chips for onboard serial ports.
> 

grumble.

These:

> +#define READ_SC(p, r)        readb((p)->membase + RD_##r)
> +#define WRITE_SC(p, r, v)    writeb((v), (p)->membase + WR_##r)

and these:

> +#define READ_SC_PORT(p, r)     read_sc_port(p, RD_PORT_##r)
> +#define WRITE_SC_PORT(p, r, v) write_sc_port(p, WR_PORT_##r, v)

really don't need to exist.  All they do is make the code harder to read.

Think of the poor reader who sees this:

		status = READ_SC_PORT(port, SR);

and then goes madly searching for "SR".  After a while, our confused reader
might think to go look at the definition of READ_SC_PORT, after which our
reader will emulate a C preprocessor in wetware and will eventually construct
then hunt down RD_PORT_SR and will then hopefully remember what the heck he was
trying to do in the first place.

This sucks.

Code is written once and is read a thousand times.  Please optimise for
reading.
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