Messages in this thread | | | Date | Mon, 15 Aug 2016 22:55:53 +0200 | From | Rask Ingemann Lambertsen <> | Subject | Re: [PATCH v2] clocksource: sun4i: Clear interrupts after stopping timer in probe function |
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On Mon, Aug 15, 2016 at 12:57:04PM +0800, Chen-Yu Tsai wrote: > The bootloader (U-boot) sometimes uses this timer for various delays. > It uses it as a ongoing counter, and does comparisons on the current > counter value. The timer counter is never stopped. > > In some cases when the user interacts with the bootloader, or lets > it idle for some time before loading Linux, the timer may expire, > and an interrupt will be pending. This results in an unexpected > interrupt when the timer interrupt is enabled by the kernel, at > which point the event_handler isn't set yet. This results in a NULL > pointer dereference exception, panic, and no way to reboot.
Thanks for tracking down this bug. It bit me too once. Now I won't wonder if it was my fault. I do wonder if there are more interrupts which need their pending status cleared in the probe function.
-- Rask Ingemann Lambertsen
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