From mboxrd@z Thu Jan  1 00:00:00 1970
From: benh@kernel.crashing.org (Benjamin Herrenschmidt)
Date: Mon, 14 Jun 2010 19:22:58 +1000
Subject: [RFC,PATCH 1/2] Add a common struct clk
In-Reply-To: <19477.52889.982995.407051@ipc1.ka-ro>
References: <1275636608.606606.450179637764.0.gpush@pororo>
	<201006111557.12249.jeremy.kerr@canonical.com>
	<19473.61547.684572.647641@ipc1.ka-ro>
	<201006111718.47426.jeremy.kerr@canonical.com>
	<19474.172.742782.972629@ipc1.ka-ro>
	<20100611095839.GC10894@pengutronix.de>
	<19474.2817.333749.485028@ipc1.ka-ro>
	<1276319643.1962.181.camel@pasglop>
	<19477.52889.982995.407051@ipc1.ka-ro>
Message-ID: <1276507378.2552.39.camel@pasglop>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, 2010-06-14 at 08:39 +0200, Lothar Wa?mann wrote:
> All implementations so far use spin_lock_irq_save()!

Nothing prevents your implementation to be a tad smarter.

> How would you be able to sleep with a mutex held?
> If you hold a lock you must not sleep, no matter what sort of lock it
> is. 

You can perfectly sleep with a mutex held. You -do- have to be careful
of course to ensure you aren't going to do silly thing like re-enter and
try to take it twice, or A->B B->A deadlocks, but in the typical case of
wanting to use a msleep rather than udelay, it works very well :-)

Cheers,
Ben.