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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Stefan Potyra <Stefan.Potyra@elektrobit.com>,
        Evgeniy Polyakov <zbr@ioremap.net>
Subject: [PATCH 3.18 45/85] w1: mxc_w1: Enable clock before calling clk_get_rate() on it
Date:   Sun,  1 Jul 2018 18:02:03 +0200
Message-Id: <20180701153124.155344258@linuxfoundation.org>
In-Reply-To: <20180701153122.365061142@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Potyra <Stefan.Potyra@elektrobit.com>

commit 955bc61328dc0a297fb3baccd84e9d3aee501ed8 upstream.

According to the API, you may only call clk_get_rate() after actually
enabling it.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: a5fd9139f74c ("w1: add 1-wire master driver for i.MX27 / i.MX31")
Signed-off-by: Stefan Potyra <Stefan.Potyra@elektrobit.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/w1/masters/mxc_w1.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

--- a/drivers/w1/masters/mxc_w1.c
+++ b/drivers/w1/masters/mxc_w1.c
@@ -113,6 +113,10 @@ static int mxc_w1_probe(struct platform_
 	if (IS_ERR(mdev->clk))
 		return PTR_ERR(mdev->clk);
 
+	err = clk_prepare_enable(mdev->clk);
+	if (err)
+		return err;
+
 	clkrate = clk_get_rate(mdev->clk);
 	if (clkrate < 10000000)
 		dev_warn(&pdev->dev,
@@ -126,12 +130,10 @@ static int mxc_w1_probe(struct platform_
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	mdev->regs = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(mdev->regs))
-		return PTR_ERR(mdev->regs);
-
-	err = clk_prepare_enable(mdev->clk);
-	if (err)
-		return err;
+	if (IS_ERR(mdev->regs)) {
+		err = PTR_ERR(mdev->regs);
+		goto out_disable_clk;
+	}
 
 	/* Software reset 1-Wire module */
 	writeb(MXC_W1_RESET_RST, mdev->regs + MXC_W1_RESET);
@@ -147,8 +149,12 @@ static int mxc_w1_probe(struct platform_
 
 	err = w1_add_master_device(&mdev->bus_master);
 	if (err)
-		clk_disable_unprepare(mdev->clk);
+		goto out_disable_clk;
+
+	return 0;
 
+out_disable_clk:
+	clk_disable_unprepare(mdev->clk);
 	return err;
 }