linux-kernel - Re: [PATCH v4] introduce macro spin_event

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Message-ID: <20090310153537.5fd5d84d@lxorguk.ukuu.org.uk>
Date:	Tue, 10 Mar 2009 15:35:37 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Timur Tabi <timur@...escale.com>
Cc:	linux-kernel@...r.kernel.org, rdreier@...co.com,
	jirislaby@...il.com, peterz@...radead.org, will.newton@...il.com,
	hancockrwd@...il.com, jeremy@...p.org
Subject: Re: [PATCH v4] introduce macro spin_event_timeout()

> This primary purpose of this macro is to poll on a hardware register until a
> status bit changes.  The timeout ensures that the loop still terminates if the
> bit doesn't change as expected.  This macro makes it easier for driver
> developers to perform this kind of operation properly.

NAK this - on a lot of platforms 1uS is the wrong timescale. Also we
shouldn't be encouraging this kind of polling by making it very easy to
write.

It might be a useful internal macro for some freescale drivers but if so
it doesn't belong in the core headers

Alan
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