linux-kernel - [PATCH v4 1/4] usb: musb: da8xx: Call earlier clk_prepare

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Date:   Fri,  4 Nov 2016 17:43:35 +0100
From:   Alexandre Bailon <abailon@...libre.com>
To:     david@...hnology.com, b-liu@...com, balbi@...nel.org
Cc:     kishon@...com, khilman@...libre.com, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, nsekhar@...com,
        Alexandre Bailon <abailon@...libre.com>
Subject: [PATCH v4 1/4] usb: musb: da8xx: Call earlier clk_prepare_enable()

The first attempt to read a register may fail because the clock may not
be enabled, and then the probe of musb driver will fail.
Call clk_prepare_enable() before the first register read.

Signed-off-by: Alexandre Bailon <abailon@...libre.com>
---
 drivers/usb/musb/da8xx.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/musb/da8xx.c b/drivers/usb/musb/da8xx.c
index 210b7e4..6749aa1 100644
--- a/drivers/usb/musb/da8xx.c
+++ b/drivers/usb/musb/da8xx.c
@@ -366,6 +366,12 @@ static int da8xx_musb_init(struct musb *musb)
 
 	musb->mregs += DA8XX_MENTOR_CORE_OFFSET;
 
+	ret = clk_prepare_enable(glue->clk);
+	if (ret) {
+		dev_err(glue->dev, "failed to enable clock\n");
+		return ret;
+	}
+
 	/* Returns zero if e.g. not clocked */
 	rev = musb_readl(reg_base, DA8XX_USB_REVISION_REG);
 	if (!rev)
@@ -377,12 +383,6 @@ static int da8xx_musb_init(struct musb *musb)
 		goto fail;
 	}
 
-	ret = clk_prepare_enable(glue->clk);
-	if (ret) {
-		dev_err(glue->dev, "failed to enable clock\n");
-		goto fail;
-	}
-
 	setup_timer(&otg_workaround, otg_timer, (unsigned long)musb);
 
 	/* Reset the controller */
@@ -392,7 +392,7 @@ static int da8xx_musb_init(struct musb *musb)
 	ret = phy_init(glue->phy);
 	if (ret) {
 		dev_err(glue->dev, "Failed to init phy.\n");
-		goto err_phy_init;
+		goto fail;
 	}
 
 	ret = phy_power_on(glue->phy);
@@ -412,9 +412,8 @@ static int da8xx_musb_init(struct musb *musb)
 
 err_phy_power_on:
 	phy_exit(glue->phy);
-err_phy_init:
-	clk_disable_unprepare(glue->clk);
 fail:
+	clk_disable_unprepare(glue->clk);
 	return ret;
 }
 
-- 
2.7.3