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SubjectRe: RTC seems broken on 2.6.38-rc1 for RTCs lacking alarms.
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On Thu, 2011-01-20 at 22:24 +0100, Geert Uytterhoeven wrote:
> On Thu, Jan 20, 2011 at 22:16, John Stultz <john.stultz@linaro.org> wrote:
> > On Thu, 2011-01-20 at 12:51 -0800, David Daney wrote:
> >> open("/dev/rtc0", O_RDONLY|O_LARGEFILE) = 3
> >> ioctl(3, PRESTO_GETMOUNT or RTC_UIE_ON, 0) = 0
> >> _newselect(4, [3], NULL, NULL, {5, 0}) = 0 (Timeout)
> >> write(2, "select() to /dev/rtc0 to wait for"..., 55select() to /dev/rtc0
> >> to wait for clock tick timed out
> >> ) = 55
> >> ioctl(3, PRESTO_SETPID or RTC_UIE_OFF, 0) = 0
> >> close(3) = 0
> >> exit_group(1) = ?
> >>
> >>
> >> The hwclock program is asking to put the clock in UIE mode and then
> >> does a select() on it. Since the alarm doesn't work, the select times out.
> >>
> >> Previously the ioctl(RTC_UIE_ON) would return EINVAL:
> >
> > Ah. Good diagnosis! Let me try to get a patch for you and Andreas to
> > test.
>
> I'm also seeing this on m68k (ARAnyM, rtc-generic).

Geert, David, Andreas,
Could you try the following? Its a bit messy of a patch doing a couple
of things:

1) Simplify the timer->enabled management by pushing it into
rtc_timer_enqueue/remove (needed cleanup for #2).

2) Properly propagating errors from __rtc_set_alarm back through
rtc_timer_enqueue and users.

3) Trivial clenaup making rtc_timer_enqueue/remove static.

4) Fixup virtualized rtc_read_alarm to check hardware capabilities and
return errors (also restores zeroing of the rtc_wkalrm stucture).

I'll be cleaning these up and breaking them into commits I can send
upward, but I wanted to make sure it resolves the issue for you.

Let me know if it fixes things.

thanks
-john

NOT FOR INCLUSION! NOT FOR INCLUSION! NOT FOR INCLUSION!
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 90384b9..db816cd 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -16,6 +16,9 @@
#include <linux/log2.h>
#include <linux/workqueue.h>

+static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
+static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
+
static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
int err;
@@ -120,12 +123,20 @@ int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;
- alarm->enabled = rtc->aie_timer.enabled;
- if (alarm->enabled)
- alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
+ if (rtc->ops == NULL)
+ err = -ENODEV;
+ else if (!rtc->ops->read_alarm)
+ err = -EINVAL;
+ else {
+ memset(alarm, 0, sizeof(struct rtc_wkalrm));
+ alarm->enabled = rtc->aie_timer.enabled;
+ if (alarm->enabled)
+ alarm->time =
+ rtc_ktime_to_tm(rtc->aie_timer.node.expires);
+ }
mutex_unlock(&rtc->ops_lock);

- return 0;
+ return err;
}
EXPORT_SYMBOL_GPL(rtc_read_alarm);

@@ -175,16 +186,14 @@ int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
return err;
if (rtc->aie_timer.enabled) {
rtc_timer_remove(rtc, &rtc->aie_timer);
- rtc->aie_timer.enabled = 0;
}
rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
rtc->aie_timer.period = ktime_set(0, 0);
if (alarm->enabled) {
- rtc->aie_timer.enabled = 1;
- rtc_timer_enqueue(rtc, &rtc->aie_timer);
+ err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
}
mutex_unlock(&rtc->ops_lock);
- return 0;
+ return err;
}
EXPORT_SYMBOL_GPL(rtc_set_alarm);

@@ -195,15 +204,15 @@ int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
return err;

if (rtc->aie_timer.enabled != enabled) {
- if (enabled) {
- rtc->aie_timer.enabled = 1;
- rtc_timer_enqueue(rtc, &rtc->aie_timer);
- } else {
+ if (enabled)
+ err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
+ else
rtc_timer_remove(rtc, &rtc->aie_timer);
- rtc->aie_timer.enabled = 0;
- }
}

+ if (err)
+ return err;
+
if (!rtc->ops)
err = -ENODEV;
else if (!rtc->ops->alarm_irq_enable)
@@ -235,12 +244,9 @@ int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
now = rtc_tm_to_ktime(tm);
rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
rtc->uie_rtctimer.period = ktime_set(1, 0);
- rtc->uie_rtctimer.enabled = 1;
- rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
- } else {
+ err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
+ } else
rtc_timer_remove(rtc, &rtc->uie_rtctimer);
- rtc->uie_rtctimer.enabled = 0;
- }

out:
mutex_unlock(&rtc->ops_lock);
@@ -488,10 +494,13 @@ EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
* Enqueues a timer onto the rtc devices timerqueue and sets
* the next alarm event appropriately.
*
+ * Sets the enabled bit on the added timer.
+ *
* Must hold ops_lock for proper serialization of timerqueue
*/
-void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
+static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
{
+ timer->enabled = 1;
timerqueue_add(&rtc->timerqueue, &timer->node);
if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
struct rtc_wkalrm alarm;
@@ -501,7 +510,13 @@ void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
schedule_work(&rtc->irqwork);
+ else if (err) {
+ timerqueue_del(&rtc->timerqueue, &timer->node);
+ timer->enabled = 0;
+ return err;
+ }
}
+ return 0;
}

/**
@@ -512,13 +527,15 @@ void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
* Removes a timer onto the rtc devices timerqueue and sets
* the next alarm event appropriately.
*
+ * Clears the enabled bit on the removed timer.
+ *
* Must hold ops_lock for proper serialization of timerqueue
*/
-void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
+static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
{
struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
timerqueue_del(&rtc->timerqueue, &timer->node);
-
+ timer->enabled = 0;
if (next == &timer->node) {
struct rtc_wkalrm alarm;
int err;
@@ -626,8 +643,7 @@ int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
timer->node.expires = expires;
timer->period = period;

- timer->enabled = 1;
- rtc_timer_enqueue(rtc, timer);
+ ret = rtc_timer_enqueue(rtc, timer);

mutex_unlock(&rtc->ops_lock);
return ret;
@@ -645,7 +661,6 @@ int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
mutex_lock(&rtc->ops_lock);
if (timer->enabled)
rtc_timer_remove(rtc, timer);
- timer->enabled = 0;
mutex_unlock(&rtc->ops_lock);
return ret;
}
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 3c995b4..bd4fbc3 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -246,8 +246,6 @@ int rtc_register(rtc_task_t *task);
int rtc_unregister(rtc_task_t *task);
int rtc_control(rtc_task_t *t, unsigned int cmd, unsigned long arg);

-void rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
-void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data);
int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
ktime_t expires, ktime_t period);



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