[PATCH 1/3] backlight: da9052: Use usleep_range() instead of msleep() for small sleeps

[PATCH 1/3] backlight: da9052: Use usleep_range() instead of msleep() for small sleeps

[Jingoo Han]

Since msleep might not sleep for the desired amount when less
than 20ms, use usleep_range.

Cc: Ashish Jangam <ashish.jangam@kpitcummins.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
---
 drivers/video/backlight/da9052_bl.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/video/backlight/da9052_bl.c b/drivers/video/backlight/da9052_bl.c
index b628d68..10485c9 100644
--- a/drivers/video/backlight/da9052_bl.c
+++ b/drivers/video/backlight/da9052_bl.c
@@ -72,7 +72,7 @@ static int da9052_adjust_wled_brightness(struct da9052_bl *wleds)
 	if (ret < 0)
 		return ret;
 
-	msleep(10);
+	usleep_range(10000, 11000);
 
 	if (wleds->brightness) {
 		ret = da9052_reg_write(wleds->da9052, wled_bank[wleds->led_reg],
-- 
1.7.1

Re: [PATCH 1/3] backlight: da9052: Use usleep_range() instead of msleep() for small sleeps

[Sachin Kamat]

Hi Jingoo,

On 6 August 2012 10:13, Jingoo Han <jg1.han@samsung.com> wrote:
> Since msleep might not sleep for the desired amount when less
> than 20ms, use usleep_range.
>
> Cc: Ashish Jangam <ashish.jangam@kpitcummins.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> Signed-off-by: Jingoo Han <jg1.han@samsung.com>
> ---
>  drivers/video/backlight/da9052_bl.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/video/backlight/da9052_bl.c b/drivers/video/backlight/da9052_bl.c
> index b628d68..10485c9 100644
> --- a/drivers/video/backlight/da9052_bl.c
> +++ b/drivers/video/backlight/da9052_bl.c
> @@ -72,7 +72,7 @@ static int da9052_adjust_wled_brightness(struct da9052_bl *wleds)
>         if (ret < 0)
>                 return ret;
>
> -       msleep(10);
> +       usleep_range(10000, 11000);

Can't we just use usleep(10000) instead?


>
>         if (wleds->brightness) {
>                 ret = da9052_reg_write(wleds->da9052, wled_bank[wleds->led_reg],
> --
> 1.7.1
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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-- 
With warm regards,
Sachin

Re: [PATCH 1/3] backlight: da9052: Use usleep_range() instead of msleep() for small sleeps

[Jingoo Han]

On Monday, August 06, 2012 1:48 PM Sachin Kamat wrote:
> 
> Hi Jingoo,
> 
> On 6 August 2012 10:13, Jingoo Han <jg1.han@samsung.com> wrote:
> > Since msleep might not sleep for the desired amount when less
> > than 20ms, use usleep_range.
> >
> > Cc: Ashish Jangam <ashish.jangam@kpitcummins.com>
> > Cc: Richard Purdie <rpurdie@rpsys.net>
> > Signed-off-by: Jingoo Han <jg1.han@samsung.com>
> > ---
> >  drivers/video/backlight/da9052_bl.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/video/backlight/da9052_bl.c b/drivers/video/backlight/da9052_bl.c
> > index b628d68..10485c9 100644
> > --- a/drivers/video/backlight/da9052_bl.c
> > +++ b/drivers/video/backlight/da9052_bl.c
> > @@ -72,7 +72,7 @@ static int da9052_adjust_wled_brightness(struct da9052_bl *wleds)
> >         if (ret < 0)
> >                 return ret;
> >
> > -       msleep(10);
> > +       usleep_range(10000, 11000);
> 
> Can't we just use usleep(10000) instead?


usleep() is not available.
For more details, refer to Documentation/timers/timers-howto.txt.


> 
> 
> >
> >         if (wleds->brightness) {
> >                 ret = da9052_reg_write(wleds->da9052, wled_bank[wleds->led_reg],
> > --
> > 1.7.1
> >
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 
> 
> 
> --
> With warm regards,
> Sachin

Re: [PATCH 1/3] backlight: da9052: Use usleep_range() instead of msleep() for small sleeps

[Mark Brown]

On Mon, Aug 06, 2012 at 01:59:38PM +0900, Jingoo Han wrote:
> On Monday, August 06, 2012 1:48 PM Sachin Kamat wrote:

> > > +       usleep_range(10000, 11000);

> > Can't we just use usleep(10000) instead?

> usleep() is not available.
> For more details, refer to Documentation/timers/timers-howto.txt.

Given how common this pattern is is it not more sensible to just
provide usleep() even if just as an inline that's something like

   void usleep(unsigned long t)
   {
   	usleep_range(t, t + (t / 10));
   }

since the usleep_range() isn't ideal for clarity (and usually the upper
bound isn't a particular concern for the driver, it just wants the usual
"delay for at least x" semantics).