On Tue, Jan 26, 2016 at 04:20:13PM -0300, Javier Martinez Canillas wrote:
> Documentation/timers/timers-howto.txt suggest to use usleep_range()
> instead of msleep() for small msec (1ms - 20ms) since msleep() will
> often sleep for 20ms for any value in that range.
>
> This is fine in this case since 16ms is the _minimum_ delay required
> by max77686 for an RTC update but by using usleep_range() instead of
> msleep(), the driver can support other RTC IP blocks with a shorter
> minimum delay (i.e: in the range of usecs instead of msecs).
>
> Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
> Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> Tested-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxx>
> ---
>
> Changes in v3:
> - Add Krzysztof Kozlowski's Tested-by tag to patch #3.
> - Add Laxman Dewangan's Acked-by tag to patch #3.
>
> Changes in v2:
> - Add Krzysztof Kozlowski's Reviewed-by tag to patch #3.
> - Fix typo error in changelog. Suggested by Krzysztof Kozlowski.
>
> drivers/rtc/rtc-max77686.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/rtc/rtc-max77686.c b/drivers/rtc/rtc-max77686.c
> index d84a50c9f7f7..025a17a95da3 100644
> --- a/drivers/rtc/rtc-max77686.c
> +++ b/drivers/rtc/rtc-max77686.c
> @@ -41,7 +41,7 @@
> #define ALARM_ENABLE_SHIFT 7
> #define ALARM_ENABLE_MASK (1 << ALARM_ENABLE_SHIFT)
>
> -#define MAX77686_RTC_UPDATE_DELAY 16
> +#define MAX77686_RTC_UPDATE_DELAY 16000
>
> enum {
> RTC_SEC = 0,
> @@ -130,7 +130,8 @@ static int max77686_rtc_update(struct max77686_rtc_info *info,
> __func__, ret, data);
> else {
> /* Minimum 16ms delay required before RTC update. */
> - msleep(MAX77686_RTC_UPDATE_DELAY);
> + usleep_range(MAX77686_RTC_UPDATE_DELAY,
> + MAX77686_RTC_UPDATE_DELAY * 2);
> }
>
> return ret;
> --
> 2.5.0
>
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