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From: jhovold@gmail.com (Johan Hovold)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/5] ARM: at91/rtc: fix boot after RTC wake-up
Date: Mon, 11 Mar 2013 19:07:55 +0100	[thread overview]
Message-ID: <1363025279-17615-2-git-send-email-jhovold@gmail.com> (raw)
In-Reply-To: <1363025279-17615-1-git-send-email-jhovold@gmail.com>

Fix failed boot after RTC wake-up by making sure RTC-interrupts are
disabled at shutdown.

The RTC-registers are not reset at shutdown when there is backup power
available, and hence the RTC-interrupt, which uses the shared system
interrupt, may be enabled during early boot. If an RTC-alarm goes off
before the RTC-driver is initialised (e.g. when waking up from an
RTC-alarm) this results in disabled system interrupts.

Without earlyprintk boot hangs after

  Uncompressing Linux... done, booting the kernel.

and earlyprintk reveals that the shared system interrupt gets disabled:

  irq 17: nobody cared (try booting with the "irqpoll" option)
  [<c000cf8c>] (unwind_backtrace+0x0/0xf0) from [<c00513ec>] (__report_bad_irq+0x20/0xe8)
  [<c00513ec>] (__report_bad_irq+0x20/0xe8) from [<c00516fc>] (note_interrupt+0x1e0/0x244)
  [<c00516fc>] (note_interrupt+0x1e0/0x244) from [<c004f980>] (handle_irq_event_percpu+0xac/0x1c4)
  [<c004f980>] (handle_irq_event_percpu+0xac/0x1c4) from [<c004faec>] (handle_irq_event+0x54/0x84)
  [<c004faec>] (handle_irq_event+0x54/0x84) from [<c0052364>] (handle_fasteoi_irq+0x84/0x154)
  [<c0052364>] (handle_fasteoi_irq+0x84/0x154) from [<c004f1f8>] (generic_handle_irq+0x20/0x30)
  [<c004f1f8>] (generic_handle_irq+0x20/0x30) from [<c0009b8c>] (handle_IRQ+0x30/0x84)
  [<c0009b8c>] (handle_IRQ+0x30/0x84) from [<c0008fa0>] (__irq_svc+0x40/0x6c)
  [<c0008fa0>] (__irq_svc+0x40/0x6c) from [<c001cd6c>] (__do_softirq+0x5c/0x164)
  [<c001cd6c>] (__do_softirq+0x5c/0x164) from [<c001d268>] (irq_exit+0x58/0x60)
  [<c001d268>] (irq_exit+0x58/0x60) from [<c0009b90>] (handle_IRQ+0x34/0x84)
  [<c0009b90>] (handle_IRQ+0x34/0x84) from [<c0008fa0>] (__irq_svc+0x40/0x6c)
  [<c0008fa0>] (__irq_svc+0x40/0x6c) from [<c03e668c>] (start_kernel+0x1d8/0x29c)
  [<c03e668c>] (start_kernel+0x1d8/0x29c) from [<70008040>] (0x70008040)
  handlers:
  [<c0012df0>] at91sam926x_pit_interrupt
  Disabling IRQ #17

Note that disabling the RTC-interrupts at shutdown fixes boot after a
clean shutdown, but that an RTC-alarm after a user (or watchdog) reset
could still prevent the system from booting.

Note also that the only way to recover from a failed boot after an
RTC-alarm is to remove any backup power (e.g. backup battery) or to
disable (or acknowledge) the RTC-interrupt manually from the bootloader.
In particular, a user-reset is not sufficient.

Tested on at91sam9g45.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/rtc/rtc-at91rm9200.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index b6469e2..936c75a 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -338,6 +338,14 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void at91_rtc_shutdown(struct platform_device *pdev)
+{
+	/* Disable all interrupts */
+	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
+					AT91_RTC_SECEV | AT91_RTC_TIMEV |
+					AT91_RTC_CALEV);
+}
+
 #ifdef CONFIG_PM
 
 /* AT91RM9200 RTC Power management control */
@@ -384,6 +392,7 @@ static const struct dev_pm_ops at91_rtc_pm = {
 
 static struct platform_driver at91_rtc_driver = {
 	.remove		= __exit_p(at91_rtc_remove),
+	.shutdown	= at91_rtc_shutdown,
 	.driver		= {
 		.name	= "at91_rtc",
 		.owner	= THIS_MODULE,
-- 
1.8.1.5

  reply	other threads:[~2013-03-11 18:07 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-08 12:51 [PATCH 0/3] ARM: at91: fix hanged boot Johan Hovold
2013-03-08 12:51 ` [PATCH 1/3] ARM: at91/rtc: fix boot after RTC wake-up Johan Hovold
2013-03-08 12:51 ` [PATCH 2/3] Revert "arm: at91: move at91rm9200 rtc header in drivers/rtc" Johan Hovold
2013-03-08 12:51 ` [PATCH 3/3] ARM: at91: fix hanged boot Johan Hovold
2013-03-08 16:02   ` [rtc-linux] " Jean-Christophe PLAGNIOL-VILLARD
2013-03-11 10:02     ` Johan Hovold
2013-03-11 11:06       ` Jean-Christophe PLAGNIOL-VILLARD
2013-03-11 18:06         ` Johan Hovold
2013-03-11 18:07           ` [PATCH v2 0/5] " Johan Hovold
2013-03-11 18:07             ` Johan Hovold [this message]
2013-03-11 18:07             ` [PATCH v2 2/5] ARM: at91/dts: add RTC nodes Johan Hovold
2013-03-11 18:07             ` [PATCH v2 3/5] ARM: at91/dts: add RTT nodes Johan Hovold
2013-03-11 18:07             ` [PATCH v2 4/5] Revert "arm: at91: move at91rm9200 rtc header in drivers/rtc" Johan Hovold
2013-03-11 18:07             ` [PATCH v2 5/5] ARM: at91: fix hanged boot Johan Hovold
2013-04-11 15:55             ` [PATCH v2 0/5] " Johan Hovold
2013-04-11 16:54               ` [rtc-linux] " Jean-Christophe PLAGNIOL-VILLARD
2013-04-12  9:33                 ` Johan Hovold
2013-04-12 12:09                   ` Nicolas Ferre
2013-10-16  9:56             ` [PATCH v3 0/3] " Johan Hovold
2013-10-16  9:56               ` [PATCH v3 1/3] ARM: at91: fix hanged boot due to early rtc-interrupt Johan Hovold
2013-11-15 11:09                 ` Nicolas Ferre
2013-10-16  9:56               ` [PATCH v3 2/3] ARM: at91: fix hanged boot due to early rtt-interrupt Johan Hovold
2013-11-15 11:10                 ` Nicolas Ferre
2013-10-16  9:56               ` [PATCH v3 3/3] ARM: at91/rtc: disable interrupts at shutdown Johan Hovold
2013-11-15 10:43                 ` Nicolas Ferre

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