[PATCH 1/3] backlight: da9052: Use usleep_range() instead ..

Jingoo Han · External Since: Dec 12, 2011 Posts: 35

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

Cc: Ashish Jangam
Cc: Richard Purdie
Signed-off-by: Jingoo Han
---
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

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Sachin Kamat · External Since: Apr 30, 2012 Posts: 18

Hi Jingoo,

On 6 August 2012 10:13, Jingoo Han wrote:
> Since msleep might not sleep for the desired amount when less
> than 20ms, use usleep_range.
>
> Cc: Ashish Jangam
> Cc: Richard Purdie
> Signed-off-by: Jingoo Han
> ---
> 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
>
>
> --
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--
With warm regards,
Sachin
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Jingoo Han · External Since: Dec 12, 2011 Posts: 35

On Monday, August 06, 2012 1:48 PM Sachin Kamat wrote:
>
> Hi Jingoo,
>
> On 6 August 2012 10:13, Jingoo Han wrote:
> > Since msleep might not sleep for the desired amount when less
> > than 20ms, use usleep_range.
> >
> > Cc: Ashish Jangam
> > Cc: Richard Purdie
> > Signed-off-by: Jingoo Han
> > ---
> > 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 RemoveThis @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

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Mark Brown · External Since: Jan 12, 2009 Posts: 550

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).
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