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SubjectRe: [PATCH] rtc: cros-ec: return -ETIME when refused to set alarms in the past
One last note:

On Sun, Feb 25, 2018 at 04:18:02PM +0800, Jeffy Chen wrote:
> We have a check in __rtc_set_alarm() to return -ETIME when the alarm
> is in the past.
>
> Since accessing a Chrome OS EC based rtc is a slow operation, we should
> do that check again inside of the EC rtc driver's .set_alarm() callback.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> ---
>
> drivers/rtc/rtc-cros-ec.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/rtc/rtc-cros-ec.c b/drivers/rtc/rtc-cros-ec.c
> index f0ea6899c731..ee0062e2d222 100644
> --- a/drivers/rtc/rtc-cros-ec.c
> +++ b/drivers/rtc/rtc-cros-ec.c
> @@ -188,6 +188,10 @@ static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> if (alarm_time < 0 || alarm_time > U32_MAX)
> return -EINVAL;
>
> + /* Don't set an alarm in the past. */
> + if ((u32)alarm_time <= current_time)
> + return -ETIME;
> +
> if (!alrm->enabled) {
> /*
> * If the alarm is being disabled, send an alarm
> @@ -196,11 +200,7 @@ static int cros_ec_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> alarm_offset = EC_RTC_ALARM_CLEAR;
> cros_ec_rtc->saved_alarm = (u32)alarm_time;
> } else {
> - /* Don't set an alarm in the past. */
> - if ((u32)alarm_time < current_time)

It's probably worth noting in the commit message that you're also fixing
the case where 'alarm_time == current_time'; in the current driver
source, it *looks* like you're setting a 0-second alarm. But in fact, 0
means EC_RTC_ALARM_CLEAR, which would disable the alarm. So you are
(correctly) returning -ETIME in that case.

Brian

> - alarm_offset = EC_RTC_ALARM_CLEAR;
> - else
> - alarm_offset = (u32)alarm_time - current_time;
> + alarm_offset = (u32)alarm_time - current_time;
> }
>
> ret = cros_ec_rtc_set(cros_ec, EC_CMD_RTC_SET_ALARM, alarm_offset);
> --
> 2.11.0
>
>

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