Date: Fri, 4 Feb 2011 13:20:40 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Richard Zhao <linuxzsc@gmail.com>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>,
        Nicolas Pitre <nicolas.pitre@linaro.org>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
        Saravana Kannan <skannan@codeaurora.org>, linux-sh@vger.kernel.org,
        Ben Herrenschmidt <benh@kernel.crashing.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Paul Mundt <lethal@linux-sh.org>, linux-kernel@vger.kernel.org,
        Dima Zavin <dmitriyz@google.com>, Ben Dooks <ben-linux@fluff.org>,
        Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= 
	<u.kleine-koenig@pengutronix.de>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: Locking in the clk API, part 2: clk_prepare/clk_unprepare
Message-ID: <20110204132040.GI14627@n2100.arm.linux.org.uk>
References: <201102011711.31258.jeremy.kerr@canonical.com> <20110204124534.GA2597@richard-laptop>
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On Fri, Feb 04, 2011 at 08:45:34PM +0800, Richard Zhao wrote:
> > == Implementation ==
> > 
> > Basically:
> > 
> > struct clk {
> > 	const struct clk_ops *ops
> > 	int                  enable_count;
> > 	spinlock_t           enable_lock;
> > 	int                  prepare_count;
> > 	struct mutex         prepare_lock;
> > };
> > 
> > int clk_enable(struct clk *clk)
> > {
> > 	int ret = 0;
> > 
> > 	spin_lock(&clk->enable_lock);
> > 	if (!clk->enable_count)
> > 		ret = clk->ops->enable(clk);
> > 
> > 	if (!ret)
> > 		clk->enable_count++;
> > 	spin_unlock(&clk->enable_lock);
> > 
> > 	return ret;
> > }
> Why do we not call parent's clk_enable in this function? For flexible? How many
> different cases is causing us to move the effert to platform clock driver?

You may notice that struct clk above doesn't have a parent.
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