linux-kernel - Re: [patch] TTY: synclink, small cleanup in dtr

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Message-ID: <20130127201947.GO16282@mwanda>
Date:	Sun, 27 Jan 2013 23:19:47 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>,
	Paul Fulghum <paulkf@...rogate.com>,
	David Howells <dhowells@...hat.com>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] TTY: synclink, small cleanup in dtr_rts()

On Sun, Jan 27, 2013 at 12:04:38PM -0800, Joe Perches wrote:
> On Sun, 2013-01-27 at 22:40 +0300, Dan Carpenter wrote:
> > There is a kind of precedence problem here, but it doesn't affect how
> > the code works because ->serial_signals is unsigned char.  We want to
> > clear two flags here.
> > 
> > #define SerialSignal_RTS            0x20     /* Request to Send */
> > #define SerialSignal_DTR            0x80     /* Data Terminal Ready */
> > 
> > Without the parenthesis then it does:
> > 
> > 	info->serial_signals &= 0x5f;
> > 
> > With the parenthesis it does:
> > 
> > 	info->serial_signals &= 0xffffff5f;
> > 
> > info->serial_signals is an unsigned char so the two statements are
> > equivalent, but it's cleaner to add the parenthesis.  In other dtr_rts()
> > functions the parenthesis are there so this makes it more consistent.
> 
> 
> Wouldn't it be clearer still to use | instead of +
> 

Yeah.  I think it would be, but adding bitflags together instead of
doing bitwise ORs is very common as well.

I would Ack the patch you sent though.

regards,
dan carpenter

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