From patchwork Thu Jul 3 09:19:06 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 366837 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id AFA57140140; Thu, 3 Jul 2014 21:03:16 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1X2enI-0000Dn-L0; Thu, 03 Jul 2014 11:03:12 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1X2dEa-0003Pe-IZ for kernel-team@lists.ubuntu.com; Thu, 03 Jul 2014 09:23:16 +0000 Received: from bl20-140-206.dsl.telepac.pt ([2.81.140.206] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1X2dEX-0005Vl-Ts; Thu, 03 Jul 2014 09:23:14 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.11 103/198] rtc: rtc-at91rm9200: fix infinite wait for ACKUPD irq Date: Thu, 3 Jul 2014 10:19:06 +0100 Message-Id: <1404379241-8590-104-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> References: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 X-Mailman-Approved-At: Thu, 03 Jul 2014 11:03:05 +0000 Cc: Boris BREZILLON , Alessandro Zummo , Linus Torvalds , Nicolas Ferre , Andrew Morton , Jean-Christophe Plagniol-Villard , Andrew Victor X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.11.10.13 -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: Luis Henriques --- 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 b86eec3ffba8..8ebf09f91fcf 100644 --- a/drivers/rtc/rtc-at91rm9200.c +++ b/drivers/rtc/rtc-at91rm9200.c @@ -48,6 +48,7 @@ struct at91_rtc_config { static const struct at91_rtc_config *at91_rtc_config; 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; @@ -161,6 +162,8 @@ 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); @@ -183,7 +186,9 @@ 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; } @@ -290,8 +295,10 @@ 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); @@ -414,6 +421,11 @@ 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); + dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n"); return 0;