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authorPaul Walmsley <paul@pwsan.com>2011-02-22 19:59:49 -0700
committerTony Lindgren <tony@atomide.com>2011-02-24 12:21:21 -0800
commitcbc9438075ca9dee3f39a2e7310f81c304b40359 (patch)
treeeac5f9ed25b96e64a664f5af441e0c238e44cd18 /arch
parentc03773206bf2249a890c4d420ed32ef500630095 (diff)
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 <paul@pwsan.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/mach-omap2/timer-gp.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c
index 7b7c2683ae7b..0fc550e7e482 100644
--- a/arch/arm/mach-omap2/timer-gp.c
+++ b/arch/arm/mach-omap2/timer-gp.c
@@ -39,6 +39,7 @@
#include <asm/mach/time.h>
#include <plat/dmtimer.h>
#include <asm/localtimer.h>
+#include <asm/sched_clock.h>
#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);
}