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| author | David Brownell <dbrownell@users.sourceforge.net> | 2008-07-23 21:30:46 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-24 10:47:34 -0700 |
| commit | 449321b39f6c6ebfa15d6da24f134240bd51db29 (patch) | |
| tree | 8ec83906bfc53883cf3da71e9e3eb8b2765eb581 | |
| parent | 773be7ee97c11fbb6b8a912a58b268dbe8a6a3fe (diff) | |
| download | lwn-449321b39f6c6ebfa15d6da24f134240bd51db29.tar.gz lwn-449321b39f6c6ebfa15d6da24f134240bd51db29.zip | |
rtc-at91rm9200: avoid spurious irqs
This fixes kernel http://bugzilla.kernel.org/show_bug.cgi?id=11112 (bogus
RTC update IRQs reported) for rtc-at91rm9200 by scrubbing old IRQ status
before enabling IRQs.
It also removes nonfunctional periodic IRQ support from this driver;
only update IRQs are reported, or provided by the hardware.
I suspect some other RTCs probably have versions of #11112; it's easy to
overlook, since most non-RTC drivers don't care about spurious IRQs:
they're not reported to userspace.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Report-by: W Unruh <unruh@physics.ubc.ca>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/rtc/rtc-at91rm9200.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c index 9c3db934cc24..cd32d05db773 100644 --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -171,8 +171,10 @@ static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) | BIN2BCD(tm.tm_mday) << 24 | AT91_RTC_DATEEN | AT91_RTC_MTHEN); - if (alrm->enabled) + if (alrm->enabled) { + at91_sys_write(AT91_RTC_SCCR, AT91_RTC_ALARM); at91_sys_write(AT91_RTC_IER, AT91_RTC_ALARM); + } pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__, at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour, @@ -191,28 +193,22 @@ static int at91_rtc_ioctl(struct device *dev, unsigned int cmd, pr_debug("%s(): cmd=%08x, arg=%08lx.\n", __func__, cmd, arg); + /* important: scrub old status before enabling IRQs */ switch (cmd) { case RTC_AIE_OFF: /* alarm off */ at91_sys_write(AT91_RTC_IDR, AT91_RTC_ALARM); break; case RTC_AIE_ON: /* alarm on */ + at91_sys_write(AT91_RTC_SCCR, AT91_RTC_ALARM); at91_sys_write(AT91_RTC_IER, AT91_RTC_ALARM); break; case RTC_UIE_OFF: /* update off */ - case RTC_PIE_OFF: /* periodic off */ at91_sys_write(AT91_RTC_IDR, AT91_RTC_SECEV); break; case RTC_UIE_ON: /* update on */ - case RTC_PIE_ON: /* periodic on */ + at91_sys_write(AT91_RTC_SCCR, AT91_RTC_SECEV); at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV); break; - case RTC_IRQP_READ: /* read periodic alarm frequency */ - ret = put_user(AT91_RTC_FREQ, (unsigned long *) arg); - break; - case RTC_IRQP_SET: /* set periodic alarm frequency */ - if (arg != AT91_RTC_FREQ) - ret = -EINVAL; - break; default: ret = -ENOIOCTLCMD; break; |