3.2.61-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Boris BREZILLON <[email protected]> commit 2fe121e1f5aa3bf31b418a9790db6c400e922291 upstream. The rtc user must wait at least 1 sec between each time/calandar update (see atmel's datasheet chapter "Updating Time/Calendar"). Use the 1Hz interrupt to update the at91_rtc_upd_rdy flag and wait for the at91_rtc_wait_upd_rdy event if the rtc is not ready. This patch fixes a deadlock in an uninterruptible wait when the RTC is updated more than once every second. AFAICT the bug is here from the beginning, but I think we should at least backport this fix to 3.10 and the following longterm and stable releases. Signed-off-by: Boris BREZILLON <[email protected]> Reported-by: Bryan Evenson <[email protected]> Tested-by: Bryan Evenson <[email protected]> Cc: Andrew Victor <[email protected]> Cc: Nicolas Ferre <[email protected]> Cc: Jean-Christophe Plagniol-Villard <[email protected]> Cc: Alessandro Zummo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [bwh: Backported to 3.2: - Adjust context - at91_rtc_write() is called at91_sys_write() - Use at91_sys_write() directly instead of the missing at91_rtc_write_ier() and at91_rtc_write_idr()] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/rtc/rtc-at91rm9200.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -36,6 +36,7 @@ #define AT91_RTC_EPOCH 1900UL /* just like arch/arm/common/rtctime.c */ static DECLARE_COMPLETION(at91_rtc_updated); +static DECLARE_COMPLETION(at91_rtc_upd_rdy); static unsigned int at91_alarm_year = AT91_RTC_EPOCH; /* @@ -97,6 +98,8 @@ static int at91_rtc_settime(struct devic 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); + wait_for_completion(&at91_rtc_upd_rdy); + /* Stop Time/Calendar from counting */ cr = at91_sys_read(AT91_RTC_CR); at91_sys_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM); @@ -119,7 +122,9 @@ static int at91_rtc_settime(struct devic /* Restart Time/Calendar */ cr = at91_sys_read(AT91_RTC_CR); + at91_sys_write(AT91_RTC_SCCR, AT91_RTC_SECEV); at91_sys_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM)); + at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV); return 0; } @@ -226,8 +231,10 @@ static irqreturn_t at91_rtc_interrupt(in if (rtsr) { /* this interrupt is shared! Is it ours? */ if (rtsr & AT91_RTC_ALARM) events |= (RTC_AF | RTC_IRQF); - if (rtsr & AT91_RTC_SECEV) - events |= (RTC_UF | RTC_IRQF); + if (rtsr & AT91_RTC_SECEV) { + complete(&at91_rtc_upd_rdy); + at91_sys_write(AT91_RTC_IDR, AT91_RTC_SECEV); + } if (rtsr & AT91_RTC_ACKUPD) complete(&at91_rtc_updated); @@ -291,6 +298,11 @@ static int __init at91_rtc_probe(struct } platform_set_drvdata(pdev, rtc); + /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy + * completion. + */ + at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV); + printk(KERN_INFO "AT91 Real Time Clock driver.\n"); return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
