From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marek Vasut <marex@denx.de>
Date: Sun, 1 Dec 2013 00:04:06 +0100
Subject: [U-Boot] [PATCH] serial: lpc32xx: send CR before LF
In-Reply-To: <20131130204347.EFF9B38015F@gemini.denx.de>
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	<201311301642.36531.marex@denx.de>
	<20131130204347.EFF9B38015F@gemini.denx.de>
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Dear Wolfgang Denk,

> Dear Marek Vasut,
> 
> In message <201311301642.36531.marex@denx.de> you wrote:
> > Dear Vladimir Zapolskiy,
> > 
> > > For LPC32XX high-speed UART it is required to send a carriage return
> > > symbol along with line feed.
> > 
> > Why ?
> 
> Because we are actually emulating a classical type writer here, and to
> start printing at the beginning of a new line requires two separate
> actions: performing a line feed (i. e. scrolling the paper one line
> up) and a crriage return (i. e. repositioning the drum such that the
> next character will be printed in column 1.
> 
> In the strict sense, the ASCII characters represent the line feed and
> '\r' the carriage return, respectively.  To print the equivalent of
> the "new line" as it is interpreted by the C standard, we have to
> translate the single C character into a two-character sequence.  You
> can trace this back to the very beginnings of Unix; you can see the
> same in Unix version 6 drivers, for example.

Thanks for such a nice explanations ;-) I still have to wonder, why do we not do 
this emulation in the serial subsystem core now, but still have such a 
duplication of code in drivers ? I guess I can answer this myself though:

a) We didn't clean this up, even if we do now have a CONFIG_SERIAL_MULTI enabled 
by default
b) There might still be people invoking the driver functions directly

There might be even more reasons, but OK, I guess I get it now.

Best regards,
Marek Vasut