Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933594AbaGVW1H (ORCPT ); Tue, 22 Jul 2014 18:27:07 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:44893 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932201AbaGVW1E (ORCPT ); Tue, 22 Jul 2014 18:27:04 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Boris BREZILLON , Andrew Victor , Nicolas Ferre , Jean-Christophe Plagniol-Villard , Alessandro Zummo , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.8 065/116] rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq Date: Tue, 22 Jul 2014 15:21:16 -0700 Message-Id: <1406067727-19683-66-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1406067727-19683-1-git-send-email-kamal@canonical.com> References: <1406067727-19683-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.27 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Boris BREZILLON 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 Reported-by: Bryan Evenson Tested-by: Bryan Evenson Cc: Andrew Victor Cc: Nicolas Ferre Cc: Jean-Christophe Plagniol-Villard Cc: Alessandro Zummo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- drivers/rtc/rtc-at91rm9200.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c index 357da6b..243d8c7 100644 --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -41,6 +41,7 @@ #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; static void __iomem *at91_rtc_regs; static int irq; @@ -104,6 +105,8 @@ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) 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_rtc_read(AT91_RTC_CR); at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM); @@ -126,7 +129,9 @@ static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) /* Restart Time/Calendar */ cr = at91_rtc_read(AT91_RTC_CR); + at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_SECEV); at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM)); + at91_rtc_write_ier(AT91_RTC_SECEV); return 0; } @@ -233,8 +238,10 @@ static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id) 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_rtc_write_idr(AT91_RTC_SECEV); + } if (rtsr & AT91_RTC_ACKUPD) complete(&at91_rtc_updated); @@ -317,6 +324,11 @@ static int __init at91_rtc_probe(struct platform_device *pdev) } platform_set_drvdata(pdev, rtc); + /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy + * completion. + */ + at91_rtc_write_ier(AT91_RTC_SECEV); + printk(KERN_INFO "AT91 Real Time Clock driver.\n"); return 0; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/