ARM: imx: return zero in case next event gets a large increment

The return of v2_set_next_event() will lead to an infinite loop in
tick_handle_oneshot_broadcast() - "goto again;" with imx6q WAIT mode
(to be enabled).  This happens because when global event did not expire
any CPU local events, the broadcast device will be rearmed to a CPU
local next_event, which could be far away from now and result in a
max_delta_tick programming in set_next_event().

Fix the problem by detecting those next events with increments larger
than 0x7fffffff, and simply return zero in that case.

It leaves mx1_2_set_next_event() unchanged since only v2_set_next_event()
will be running with imx6q WAIT mode support.

Thanks Russell King for helping understand the problem.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

diff --git a/arch/arm/mach-imx/time.c b/arch/arm/mach-imx/time.c
index f017302f6d09c94d5d97d4d63f47311d8ace4e7a..5d7eb482efd327d06de0fcc8b59601d8b151eb21 100644 (file)
--- a/arch/arm/mach-imx/time.c
+++ b/arch/arm/mach-imx/time.c
@@ -152,7 +152,8 @@ static int v2_set_next_event(unsigned long evt,
 
        __raw_writel(tcmp, timer_base + V2_TCMP);
 
-       return (int)(tcmp - __raw_readl(timer_base + V2_TCN)) < 0 ?
+       return evt < 0x7fffffff &&
+               (int)(tcmp - __raw_readl(timer_base + V2_TCN)) < 0 ?
                                -ETIME : 0;
 }