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In-Reply-To: <20110201105449.GY1147@pengutronix.de>
References: <201102011711.31258.jeremy.kerr@canonical.com>
	<20110201105449.GY1147@pengutronix.de>
Date: Tue, 1 Feb 2011 22:05:56 +0900
Message-ID: <AANLkTimayMAfr+zA6uO_yUmZqsOLmJ3fiiS696mL_evn@mail.gmail.com>
Subject: Re: Locking in the clk API, part 2: clk_prepare/clk_unprepare
From: Jassi Brar <jassisinghbrar@gmail.com>
To: =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
	<u.kleine-koenig@pengutronix.de>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>,
        Nicolas Pitre <nicolas.pitre@linaro.org>,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
        Russell King <linux@arm.linux.org.uk>, 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>,
        Saravana Kannan <skannan@codeaurora.org>,
        Ben Dooks <ben-linux@fluff.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        linux-arm-kernel@lists.infradead.org
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2011/2/1 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:

.....

> Do you plan to handle the case that clk_enable is called while prepare
> isn't completed (considering the special case "not called at all")?
> Maybe BUG_ON(clk->ops->prepare && !clk->prepare_count)?
Sounds better than the second option.

> Alternatively don't force the sleep in clk_prepare (e.g. by protecting
> prepare_count by a spinlock (probably enable_lock)) and call clk_prepare
> before calling clk->ops->enable?
That might result in a driver working on some platforms(those have
atomic clk_prepare)
and not on others(those have sleeping).


Njoi!
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