linux-kernel - [PATCH v2] w1: mxc_w1: Enable clock before calling clk_get

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Date:   Wed, 2 May 2018 10:55:31 +0200
From:   Stefan Potyra <Stefan.Potyra@...ktrobit.com>
To:     Evgeniy Polyakov <zbr@...emap.net>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "ldv-project@...uxtesting.org" <ldv-project@...uxtesting.org>,
        "sil2review@...ts.osadl.org" <sil2review@...ts.osadl.org>
Subject: [PATCH v2] w1: mxc_w1: Enable clock before calling clk_get_rate() on
 it

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

diff --git a/drivers/w1/masters/mxc_w1.c b/drivers/w1/masters/mxc_w1.c
index 74f2e6e6202a..8851d441e5fd 100644
--- a/drivers/w1/masters/mxc_w1.c
+++ b/drivers/w1/masters/mxc_w1.c
@@ -112,6 +112,10 @@ static int mxc_w1_probe(struct platform_device *pdev)
 	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,
@@ -125,12 +129,10 @@ static int mxc_w1_probe(struct platform_device *pdev)
 
 	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);
@@ -146,8 +148,12 @@ static int mxc_w1_probe(struct platform_device *pdev)
 
 	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;
 }
 
-- 
2.17.0


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