linux-kernel - [RFC, PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics

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Date:	Wed, 09 Feb 2011 14:41:33 +0800
From:	Jeremy Kerr <jeremy.kerr@...onical.com>
To:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Dima Zavin <dmitriyz@...gle.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	<linux-sh@...r.kernel.org>,
	Ben Herrenschmidt <benh@...nel.crashing.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Paul Mundt <lethal@...ux-sh.org>,
	Saravana Kannan <skannan@...eaurora.org>,
	Ben Dooks <ben-linux@...ff.org>,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Russell King <linux@....linux.org.uk>
Subject: [RFC,
	PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics

This change adds warnings to check for:

 1) enabling a clock that hasn't been prepared; and

 2) unpreparing a clock that is still enabled

While the correctness can't be guaranteed, the warnings should cover
most situations, and won't indicate false positives.

Signed-off-by: Jeremy Kerr <jeremy.kerr@...onical.com>

---
 drivers/clk/clk.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index bbbdb0d..8c96623 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -29,6 +29,8 @@ EXPORT_SYMBOL_GPL(clk_prepare);
 
 void clk_unprepare(struct clk *clk)
 {
+	WARN_ON(clk->enable_count != 0);
+
 	mutex_lock(&clk->prepare_lock);
 
 	WARN_ON(clk->prepare_count == 0);
@@ -45,6 +47,8 @@ int clk_enable(struct clk *clk)
 	unsigned long flags;
 	int ret = 0;
 
+	WARN_ON(clk->prepare_count == 0);
+
 	spin_lock_irqsave(&clk->enable_lock, flags);
 	if (clk->enable_count == 0 && clk->ops->enable)
 		ret = clk->ops->enable(clk);
--
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