From mboxrd@z Thu Jan  1 00:00:00 1970
From: jamie@jamieiles.com (Jamie Iles)
Date: Wed, 5 Jan 2011 17:25:01 +0000
Subject: [PATCH v3 08/10] ARM: mxs: add ocotp read function
In-Reply-To: <20110105164409.GV25121@pengutronix.de>
References: <1294236457-17476-1-git-send-email-shawn.guo@freescale.com>
	<1294236457-17476-9-git-send-email-shawn.guo@freescale.com>
	<20110105161235.GA2112@gallagher>
	<20110105164409.GV25121@pengutronix.de>
Message-ID: <20110105172501.GB2112@gallagher>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Jan 05, 2011 at 05:44:09PM +0100, Uwe Kleine-K?nig wrote:
> Hello Jamie,
> On Wed, Jan 05, 2011 at 04:16:46PM +0000, Jamie Iles wrote:
> > On Wed, Jan 05, 2011 at 10:07:35PM +0800, Shawn Guo wrote:
> > > +	/* check both BUSY and ERROR cleared */
> > > +	while ((__raw_readl(ocotp_base) &
> > > +		(BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)) && --timeout)
> > > +		/* nothing */;
> > 
> > Is it worth using cpu_relax() in these polling loops?
> I don't know what cpu_relax does for other platforms, but on ARM it's
> just a memory barrier which AFAICT doesn't help here at all (which
> doesn't need to be correct).  Why do you think it would be better?

Well I don't see that there's anything broken without cpu_relax() but 
using cpu_relax() seems to be the most common way of doing busy polling 
loops that I've seen. It's also a bit easier to read than a comment and 
semi-colon. Perhaps it's just personal preference.

Jamie