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Date: Fri, 8 Mar 2013 13:51:40 +0100 From: Johan Hovold <jhovold@...il.com> To: Nicolas Ferre <nicolas.ferre@...el.com> Cc: Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>, Andrew Victor <linux@...im.org.za>, Alessandro Zummo <a.zummo@...ertech.it>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com, Johan Hovold <jhovold@...il.com> Subject: [PATCH 0/3] ARM: at91: fix hanged boot These patches fix a few severe issues affecting most AT91 SOCs where boot can hang after a non-general reset, and where the only way to get the system booting again is to do a general reset -- something which could require physically removing any backup battery. The problems stem from the fact that the RTC and RTT-peripherals are powered by backup power (VDDBU) and are not reset on wake-up, user, watchdog or software reset. Consequently, RTC and RTT-alarms and their interrupts may be enabled at boot, leading to a system lock-up when an interrupt arrives on the shared system-interrupt line before the appropriate handler (e.g. RTC-driver) has been installed. The easiest way to trigger this is to simply wake up from an RTC-alarm on at91sam9g45. The RTC-driver currently does not disable interrupts at shutdown so even after a clean shut-down the system will always hang after waking up. The first patch fixes this very general case of RTC-wake up after a clean shutdown in the RTC-driver and is marked for stable as it is perfectly straight-forward. [ Note that the other, RTT-based, AT91 RTC-driver already disables its interrupts at shutdown. ] The more general problem can be triggered, for example, by doing a user-reset while updating the RTC-time or if an RTC or RTT-alarm goes off after a non-clean shutdown. To fix this I propose that arch-code should mask the relevant interrupts at early boot, and this is what the third patch does. To access the RTC-registers I choose to revert a recent patch that moved the register definitions to drivers/rtc. Arguably, the interrupts could also be disabled in bootloaders, but I strongly suggest fixing it in the kernel once and for all. By adding a new, mandatory AT91 SOC-initialiser (rather extending init) it will not be overlooked when adding new SOCs either. The patches have been tested on at91sam9263 and at91sam9g45, and compile-tested for the other SOCs. Johan Johan Hovold (3): ARM: at91/rtc: fix boot after RTC wake-up Revert "arm: at91: move at91rm9200 rtc header in drivers/rtc" ARM: at91: fix hanged boot arch/arm/mach-at91/at91rm9200.c | 9 ++++ arch/arm/mach-at91/at91sam9260.c | 6 +++ arch/arm/mach-at91/at91sam9261.c | 6 +++ arch/arm/mach-at91/at91sam9263.c | 7 +++ arch/arm/mach-at91/at91sam9g45.c | 7 +++ arch/arm/mach-at91/at91sam9n12.c | 6 +++ arch/arm/mach-at91/at91sam9rl.c | 7 +++ arch/arm/mach-at91/at91sam9x5.c | 6 +++ arch/arm/mach-at91/generic.h | 2 + arch/arm/mach-at91/include/mach/at91_rtc.h | 75 +++++++++++++++++++++++++++ arch/arm/mach-at91/include/mach/at91sam9n12.h | 5 ++ arch/arm/mach-at91/include/mach/at91sam9x5.h | 5 ++ arch/arm/mach-at91/setup.c | 31 +++++++++++ arch/arm/mach-at91/soc.h | 1 + drivers/rtc/rtc-at91rm9200.c | 11 +++- drivers/rtc/rtc-at91rm9200.h | 75 --------------------------- 16 files changed, 183 insertions(+), 76 deletions(-) create mode 100644 arch/arm/mach-at91/include/mach/at91_rtc.h delete mode 100644 drivers/rtc/rtc-at91rm9200.h -- 1.8.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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