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authorJohan Hovold <jhovold@gmail.com>2013-10-16 13:56:15 +0400
committerNicolas Ferre <nicolas.ferre@atmel.com>2013-11-15 15:13:33 +0400
commit94c4c79f2f1acca6e69a50bff5a7d9027509c16b (patch)
tree85b5fdb02f99edb8b8f4368ea932c4d149fc9e1f /drivers/accessibility
parent6de714c21a8ea315fffba6a93bbe537f4c1bf4f0 (diff)
downloadlinux-94c4c79f2f1acca6e69a50bff5a7d9027509c16b.tar.xz
ARM: at91: fix hanged boot due to early rtt-interrupt
Make sure the RTT-interrupts are masked at boot by adding a new helper function to be used at SOC-init. This fixes hanged boot on all AT91 SOCs with an RTT, for example, if an RTT-alarm goes off after a non-clean shutdown (e.g. when using RTC wakeup). The RTC and RTT-peripherals are powered by backup power (VDDBU) (on all AT91 SOCs but RM9200) and are not reset on wake-up, user, watchdog or software reset. This means that their interrupts may be enabled during early boot if, for example, they where not disabled during a previous shutdown (e.g. due to a buggy driver or a non-clean shutdown such as a user reset). Furthermore, an RTC or RTT-alarm may also be active. The RTC and RTT-interrupts use the shared system-interrupt line, which is also used by the PIT, and if an interrupt occurs before a handler (e.g. RTC-driver) has been installed this leads to the system interrupt being disabled and prevents the system from booting. Note that when boot hangs due to an early RTC or RTT-interrupt, the only way to get the system to start again is to remove the backup power (e.g. battery) or to disable the interrupt manually from the bootloader. In particular, a user reset is not sufficient. Signed-off-by: Johan Hovold <jhovold@gmail.com> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Cc: stable@vger.kernel.org # 3.11.x
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