linux-kernel - [PATCH v2 4/9] net: stmmac: Balance PTP reference clock enable/disable

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Date:   Fri, 10 Mar 2017 17:34:56 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Mikko Perttunen <cyndis@...si.fi>, netdev@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/9] net: stmmac: Balance PTP reference clock enable/disable

From: Thierry Reding <treding@...dia.com>

clk_prepare_enable() and clk_disable_unprepare() for this clock aren't
properly balanced, which can trigger a WARN_ON() in the common clock
framework.

Reviewed-By: Joao Pinto <jpinto@...opsys.com>
Signed-off-by: Thierry Reding <treding@...dia.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 4 ++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 1 -
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 6060410d2b9e..ce6d7e791f3f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1711,6 +1711,10 @@ static int stmmac_hw_setup(struct net_device *dev, bool init_ptp)
 	stmmac_mmc_setup(priv);
 
 	if (init_ptp) {
+		ret = clk_prepare_enable(priv->plat->clk_ptp_ref);
+		if (ret < 0)
+			netdev_warn(priv->dev, "failed to enable PTP reference clock: %d\n", ret);
+
 		ret = stmmac_init_ptp(priv);
 		if (ret == -EOPNOTSUPP)
 			netdev_warn(priv->dev, "PTP not supported by HW\n");
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index f2d94eafeb0a..fe49c3105755 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -365,7 +365,6 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 		plat->clk_ptp_ref = NULL;
 		dev_warn(&pdev->dev, "PTP uses main clock\n");
 	} else {
-		clk_prepare_enable(plat->clk_ptp_ref);
 		plat->clk_ptp_rate = clk_get_rate(plat->clk_ptp_ref);
 		dev_dbg(&pdev->dev, "PTP rate %d\n", plat->clk_ptp_rate);
 	}
-- 
2.12.0