Messages in this thread | | | Date | Thu, 11 Apr 2013 17:55:05 +0200 | From | Johan Hovold <> | Subject | Re: [PATCH v2 0/5] ARM: at91: fix hanged boot |
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On Mon, Mar 11, 2013 at 07:07:54PM +0100, Johan Hovold wrote: > 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.
Have you had time to look at these patches yet, Nicolas?
I don't think not having decided on the path forward for DT-support for rtc-at91sam9 needs to be a blocker. The rtt-nodes will be needed in any case.
I could respin the series on top of the DT-patch for rtc-at91rm9200, and add interrupt and status-disabled properties to the DT-nodes as well.
Thanks, Johan
> 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 > before enabling the system interrupt at early boot, and this is what > the fifth patch does. To access the RTC-registers I choose to revert a > recent patch that moved the register definitions to drivers/rtc. > > Arguably, the relevant interrupts could also be disabled in bootloaders, > but I suggest fixing it in the kernel once and for all. > > The patches have been tested on at91sam9263 and at91sam9g45 (non-DT), > and compile-tested for the other SOCs and DT. > > Johan > > > v2: > - add DT-support > - make sys_irq_mask non-mandatory > > > Johan Hovold (5): > ARM: at91/rtc: fix boot after RTC wake-up > ARM: at91/dts: add RTC nodes > ARM: at91/dts: add RTT nodes > Revert "arm: at91: move at91rm9200 rtc header in drivers/rtc" > ARM: at91: fix hanged boot
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