[PATCH] Change comment in include linux/clk.h

[PATCH] Change comment in include linux/clk.h

[Haavard Skinnemoen]

From: Alex Raimondi <raimondi@miromico.ch>

clk_get and clk_put may not be used from within interrupt
context. Change comment to this function.

Signed-off-by: Alex Raimondi <raimondi@miromico.ch>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
---
I see several ARM implementation using mutexes for locking in these
functions. So I assume we never want to call them from interrupt
context, right?

 include/linux/clk.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/include/linux/clk.h b/include/linux/clk.h
index 5ca8c6f..7787773 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -35,6 +35,8 @@ struct clk;
  * clk_get may return different clock producers depending on @dev.)
  *
  * Drivers must assume that the clock source is not enabled.
+ *
+ * clk_get should not be called from within interrupt context.
  */
 struct clk *clk_get(struct device *dev, const char *id);
 
@@ -76,6 +78,8 @@ unsigned long clk_get_rate(struct clk *clk);
  * Note: drivers must ensure that all clk_enable calls made on this
  * clock source are balanced by clk_disable calls prior to calling
  * this function.
+ *
+ * clk_put should not be called from within interrupt context.
  */
 void clk_put(struct clk *clk);
 
-- 
1.5.6.5

Re: [PATCH] Change comment in include linux/clk.h

[Russell King]

On Sun, Oct 05, 2008 at 09:20:38PM +0200, Haavard Skinnemoen wrote:
> From: Alex Raimondi <raimondi@miromico.ch>
> 
> clk_get and clk_put may not be used from within interrupt
> context. Change comment to this function.
> 
> Signed-off-by: Alex Raimondi <raimondi@miromico.ch>
> Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
> ---
> I see several ARM implementation using mutexes for locking in these
> functions. So I assume we never want to call them from interrupt
> context, right?

Correct.  I'm not sure why anyone would even consider doing so.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

> 
>  include/linux/clk.h |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/clk.h b/include/linux/clk.h
> index 5ca8c6f..7787773 100644
> --- a/include/linux/clk.h
> +++ b/include/linux/clk.h
> @@ -35,6 +35,8 @@ struct clk;
>   * clk_get may return different clock producers depending on @dev.)
>   *
>   * Drivers must assume that the clock source is not enabled.
> + *
> + * clk_get should not be called from within interrupt context.
>   */
>  struct clk *clk_get(struct device *dev, const char *id);
>  
> @@ -76,6 +78,8 @@ unsigned long clk_get_rate(struct clk *clk);
>   * Note: drivers must ensure that all clk_enable calls made on this
>   * clock source are balanced by clk_disable calls prior to calling
>   * this function.
> + *
> + * clk_put should not be called from within interrupt context.
>   */
>  void clk_put(struct clk *clk);
>  
> -- 
> 1.5.6.5
> 

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:

Re: [PATCH] Change comment in include linux/clk.h

[Haavard Skinnemoen]

Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> > I see several ARM implementation using mutexes for locking in these
> > functions. So I assume we never want to call them from interrupt
> > context, right?  
> 
> Correct.  I'm not sure why anyone would even consider doing so.

I can't think of any reason to do so either, but having the comment
there makes me feel safer about having calls that might sleep or
irq-unsafe spinlocks in the implementation.

Haavard