Re: State of LDP3430 platform

Paul Walmsley
2011-01-18T19:36:28Z

Here's a slightly updated version of this patch, fixing a bug in one of
the comments, and revising the commit message. There's no functional
difference between this and the previous version of this patch.

- Paul

[PATCH] OMAP: counter_32k: init clocksource as part of machine timer init

After commit dc548fbbd2ecd0fc3b02301d551e5f8e19ae58fd ("ARM: omap: convert
sched_clock() to use new infrastructure"), OMAPs that use the 32KiHz
"synchronization timer" as their clocksource crash during boot:

[ 0.000000] OMAP clockevent source: GPTIMER1 at 32768 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 Tainted: G W (2.6.37-07734-g2467802 #7)
[ 0.000000] PC is at 0x0
[ 0.000000] LR is at sched_clock_poll+0x2c/0x3c
[ 0.000000] pc : [<00000000>] lr : [<c0060b74>] psr: 600001d3
[ 0.000000] sp : c058bfd0 ip : c058a000 fp : 00000000
[ 0.000000] r10: 00000000 r9 : 411fc092 r8 : 800330c8
[ 0.000000] r7 : c05a08e0 r6 : c0034c48 r5 : c05ffc40 r4 : c0034c4c
[ 0.000000] r3 : c05ffe6c r2 : c05a0bc0 r1 : c059f098 r0 : 00000000
[ 0.000000] Flags: nZCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel
[ 0.000000] Control: 10c53c7f Table: 8000404a DAC: 00000017

This is due to the recent ARM init_sched_clock() changes and the late
initialization of the counter_32k clock source. More information here:

http://marc.info/?l=linux-omap&m=129513468605208&w=2

Fix by initializing the counter_32k clocksource during the machine timer
initialization.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Thomas Weber <weber@corscience.de>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
---
arch/arm/mach-omap1/time.c | 7 +++++++
arch/arm/mach-omap2/timer-gp.c | 10 ++++++++--
arch/arm/plat-omap/counter_32k.c | 3 +--
arch/arm/plat-omap/include/plat/common.h | 1 +
4 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-omap1/time.c b/arch/arm/mach-omap1/time.c
index ed7a61f..6ec65e5 100644
--- a/arch/arm/mach-omap1/time.c
+++ b/arch/arm/mach-omap1/time.c
@@ -244,6 +244,13 @@ static void __init omap_timer_init(void)

omap_init_mpu_timer(rate);
omap_init_clocksource(rate);
+ /*
+ * XXX Since this file seems to deal mostly with the MPU timer,
+ * this doesn't seem like the correct place for the sync timer
+ * clocksource init.
+ */
+ if (!cpu_is_omap7xx() && !cpu_is_omap15xx())
+ omap_init_clocksource_32k();
}

struct sys_timer omap_timer = {
diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c
index 4e48e78..7b7c268 100644
--- a/arch/arm/mach-omap2/timer-gp.c
+++ b/arch/arm/mach-omap2/timer-gp.c
@@ -42,6 +42,8 @@

#include "timer-gp.h"

+#include <plat/common.h>
+
/* MAX_GPTIMER_ID: number of GPTIMERs on the chip */
#define MAX_GPTIMER_ID 12

@@ -176,10 +178,14 @@ static void __init omap2_gp_clockevent_init(void)
/*
* When 32k-timer is enabled, don't use GPTimer for clocksource
* instead, just leave default clocksource which uses the 32k
- * sync counter. See clocksource setup in see plat-omap/common.c.
+ * sync counter. See clocksource setup in plat-omap/counter_32k.c
*/

-static inline void __init omap2_gp_clocksource_init(void) {}
+static void __init omap2_gp_clocksource_init(void)
+{
+ omap_init_clocksource_32k();
+}
+
#else
/*
* clocksource
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index ea46440..0367998 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -160,7 +160,7 @@ void read_persistent_clock(struct timespec *ts)
*ts = *tsp;
}

-static int __init omap_init_clocksource_32k(void)
+int __init omap_init_clocksource_32k(void)
{
static char err[] __initdata = KERN_ERR
"%s: can't register clocksource!\n";
@@ -195,7 +195,6 @@ static int __init omap_init_clocksource_32k(void)
}
return 0;
}
-arch_initcall(omap_init_clocksource_32k);

#endif /* !(defined(CONFIG_ARCH_OMAP730) || defined(CONFIG_ARCH_OMAP15XX)) */

diff --git a/arch/arm/plat-omap/include/plat/common.h b/arch/arm/plat-omap/include/plat/common.h
index 6b8088e..84c707f 100644
--- a/arch/arm/plat-omap/include/plat/common.h
+++ b/arch/arm/plat-omap/include/plat/common.h
@@ -35,6 +35,7 @@ struct sys_timer;

extern void omap_map_common_io(void);
extern struct sys_timer omap_timer;
+extern int __init omap_init_clocksource_32k(void);

extern void omap_reserve(void);

--
1.7.2.3