[PATCH 0/3] ARM: at91: fix hanged boot
Johan Hovold
jhovold at gmail.com
Fri Mar 8 07:51:40 EST 2013
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
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