[PATCH v3] ARM: davinci: da8xx: Fix sleeping function called from invalid context

[PATCH v3] ARM: davinci: da8xx: Fix sleeping function called from invalid context

[Alexandre Bailon]

Everytime the usb20 phy is enabled, there is a
"sleeping function called from invalid context" BUG.

clk_enable() from arch/arm/mach-davinci/clock.c uses spin_lock_irqsave()
before to invoke the callback usb20_phy_clk_enable().
usb20_phy_clk_enable() uses clk_get() and clk_enable_prepapre()
which may sleep.
Move clk_get() to da8xx_register_usb20_phy_clk() and
replace clk_prepare_enable() by clk_enable().

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
---
 arch/arm/mach-davinci/usb-da8xx.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/arm/mach-davinci/usb-da8xx.c b/arch/arm/mach-davinci/usb-da8xx.c
index b010e5f..bfb55b9 100644
--- a/arch/arm/mach-davinci/usb-da8xx.c
+++ b/arch/arm/mach-davinci/usb-da8xx.c
@@ -156,23 +156,18 @@ int __init da8xx_register_usb_refclkin(int rate)
 	return 0;
 }
 
+static struct clk *usb20_clk;
+
 static void usb20_phy_clk_enable(struct clk *clk)
 {
-	struct clk *usb20_clk;
 	int err;
 	u32 val;
 	u32 timeout = 500000; /* 500 msec */
 
 	val = readl(DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP2_REG));
 
-	usb20_clk = clk_get(&da8xx_usb20_dev.dev, "usb20");
-	if (IS_ERR(usb20_clk)) {
-		pr_err("could not get usb20 clk: %ld\n", PTR_ERR(usb20_clk));
-		return;
-	}
-
 	/* The USB 2.O PLL requires that the USB 2.O PSC is enabled as well. */
-	err = clk_prepare_enable(usb20_clk);
+	err = clk_enable(usb20_clk);
 	if (err) {
 		pr_err("failed to enable usb20 clk: %d\n", err);
 		clk_put(usb20_clk);
@@ -197,8 +192,7 @@ static void usb20_phy_clk_enable(struct clk *clk)
 
 	pr_err("Timeout waiting for USB 2.0 PHY clock good\n");
 done:
-	clk_disable_unprepare(usb20_clk);
-	clk_put(usb20_clk);
+	clk_disable(usb20_clk);
 }
 
 static void usb20_phy_clk_disable(struct clk *clk)
@@ -287,9 +281,16 @@ int __init da8xx_register_usb20_phy_clk(bool use_usb_refclkin)
 	struct clk *parent;
 	int ret = 0;
 
+	usb20_clk = clk_get(&da8xx_usb20_dev.dev, "usb20");
+	ret = PTR_ERR_OR_ZERO(usb20_clk);
+	if (ret)
+		return ret;
+
 	parent = clk_get(NULL, use_usb_refclkin ? "usb_refclkin" : "pll0_aux");
-	if (IS_ERR(parent))
+	if (IS_ERR(parent)) {
+		clk_put(usb20_clk);
 		return PTR_ERR(parent);
+	}
 
 	usb20_phy_clk.parent = parent;
 	ret = clk_register(&usb20_phy_clk);
-- 
2.7.3

[PATCH v3] ARM: davinci: da8xx: Fix sleeping function called from invalid context

[David Lechner]

On 12/01/2016 11:12 AM, Alexandre Bailon wrote:
> Everytime the usb20 phy is enabled, there is a

Every time is two words

> "sleeping function called from invalid context" BUG.
>
> clk_enable() from arch/arm/mach-davinci/clock.c uses spin_lock_irqsave()
> before to invoke the callback usb20_phy_clk_enable().
> usb20_phy_clk_enable() uses clk_get() and clk_enable_prepapre()
> which may sleep.
> Move clk_get() to da8xx_register_usb20_phy_clk() and
> replace clk_prepare_enable() by clk_enable().
>
> Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
> ---
>  arch/arm/mach-davinci/usb-da8xx.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm/mach-davinci/usb-da8xx.c b/arch/arm/mach-davinci/usb-da8xx.c
> index b010e5f..bfb55b9 100644
> --- a/arch/arm/mach-davinci/usb-da8xx.c
> +++ b/arch/arm/mach-davinci/usb-da8xx.c
> @@ -156,23 +156,18 @@ int __init da8xx_register_usb_refclkin(int rate)
>  	return 0;
>  }
>
> +static struct clk *usb20_clk;

Not a serious issue, but I would rather have the global variable 
declared at the beginning of the file to make it more obvious there is a 
global variable.

> +
>  static void usb20_phy_clk_enable(struct clk *clk)
>  {
> -	struct clk *usb20_clk;
>  	int err;
>  	u32 val;
>  	u32 timeout = 500000; /* 500 msec */
>
>  	val = readl(DA8XX_SYSCFG0_VIRT(DA8XX_CFGCHIP2_REG));
>
> -	usb20_clk = clk_get(&da8xx_usb20_dev.dev, "usb20");
> -	if (IS_ERR(usb20_clk)) {
> -		pr_err("could not get usb20 clk: %ld\n", PTR_ERR(usb20_clk));
> -		return;
> -	}
> -
>  	/* The USB 2.O PLL requires that the USB 2.O PSC is enabled as well. */
> -	err = clk_prepare_enable(usb20_clk);
> +	err = clk_enable(usb20_clk);
>  	if (err) {
>  		pr_err("failed to enable usb20 clk: %d\n", err);
>  		clk_put(usb20_clk);
> @@ -197,8 +192,7 @@ static void usb20_phy_clk_enable(struct clk *clk)
>
>  	pr_err("Timeout waiting for USB 2.0 PHY clock good\n");
>  done:
> -	clk_disable_unprepare(usb20_clk);
> -	clk_put(usb20_clk);
> +	clk_disable(usb20_clk);
>  }
>
>  static void usb20_phy_clk_disable(struct clk *clk)
> @@ -287,9 +281,16 @@ int __init da8xx_register_usb20_phy_clk(bool use_usb_refclkin)
>  	struct clk *parent;
>  	int ret = 0;

No longer need to initialize ret here.

>
> +	usb20_clk = clk_get(&da8xx_usb20_dev.dev, "usb20");
> +	ret = PTR_ERR_OR_ZERO(usb20_clk);
> +	if (ret)
> +		return ret;
> +
>  	parent = clk_get(NULL, use_usb_refclkin ? "usb_refclkin" : "pll0_aux");
> -	if (IS_ERR(parent))
> +	if (IS_ERR(parent)) {

why not use ret = PTR_ERR_OR_ZERO(parent) pattern here too?

> +		clk_put(usb20_clk);

The global usb20_clk is no longer valid after this. Should we set it to 
NULL here?

>  		return PTR_ERR(parent);
> +	}
>
>  	usb20_phy_clk.parent = parent;
>  	ret = clk_register(&usb20_phy_clk);
>

[PATCH v3] ARM: davinci: da8xx: Fix sleeping function called from invalid context

[Sekhar Nori]

On Thursday 01 December 2016 11:17 PM, David Lechner wrote:
> 
>> +        clk_put(usb20_clk);
> 
> The global usb20_clk is no longer valid after this. Should we set it to
> NULL here?

No need of this. Also, NULL is valid clock handle.

Thanks,
Sekhar