From cbc9438075ca9dee3f39a2e7310f81c304b40359 Mon Sep 17 00:00:00 2001 From: Paul Walmsley Date: Tue, 22 Feb 2011 19:59:49 -0700 Subject: [PATCH] OMAP2+: clocksource: fix crash on boot when !CONFIG_OMAP_32K_TIMER OMAP2+ kernels built without CONFIG_OMAP_32K_TIMER crash on boot after the 2.6.38 sched_clock changes: [ 0.000000] OMAP clockevent source: GPTIMER1 at 13000000 Hz [ 0.000000] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 0.000000] pgd = c0004000 [ 0.000000] [00000000] *pgd=00000000 [ 0.000000] Internal error: Oops: 80000005 [#1] SMP [ 0.000000] last sysfs file: [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 Not tainted (2.6.38-rc5-00057-g04aa67d #152) [ 0.000000] PC is at 0x0 [ 0.000000] LR is at sched_clock_poll+0x2c/0x3c Without CONFIG_OMAP_32K_TIMER, the kernel has an clockevent and clocksource resolution about three orders of magnitude higher than with CONFIG_OMAP_32K_TIMER set. The tradeoff is that the lowest power consumption states are not available. Fix by calling init_sched_clock() from the GPTIMER clocksource init code. Signed-off-by: Paul Walmsley Signed-off-by: Tony Lindgren --- arch/arm/mach-omap2/timer-gp.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c index 7b7c2683ae7..0fc550e7e48 100644 --- a/arch/arm/mach-omap2/timer-gp.c +++ b/arch/arm/mach-omap2/timer-gp.c @@ -39,6 +39,7 @@ #include #include #include +#include #include "timer-gp.h" @@ -190,6 +191,7 @@ static void __init omap2_gp_clocksource_init(void) /* * clocksource */ +static DEFINE_CLOCK_DATA(cd); static struct omap_dm_timer *gpt_clocksource; static cycle_t clocksource_read_cycles(struct clocksource *cs) { @@ -204,6 +206,15 @@ static struct clocksource clocksource_gpt = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static void notrace dmtimer_update_sched_clock(void) +{ + u32 cyc; + + cyc = omap_dm_timer_read_counter(gpt_clocksource); + + update_sched_clock(&cd, cyc, (u32)~0); +} + /* Setup free-running counter for clocksource */ static void __init omap2_gp_clocksource_init(void) { @@ -224,6 +235,8 @@ static void __init omap2_gp_clocksource_init(void) omap_dm_timer_set_load_start(gpt, 1, 0); + init_sched_clock(&cd, dmtimer_update_sched_clock, 32, tick_rate); + if (clocksource_register_hz(&clocksource_gpt, tick_rate)) printk(err2, clocksource_gpt.name); } -- 2.46.0