[PATCH] avr32: balance cpu_idle_poll_ctrl calls

From: Gabor Juhos
Date: Wed Sep 25 2013 - 05:31:31 EST

Since commit 01426478df3a8791ff5c8b6b82d409e699cfaf38
(avr32: Use generic idle loop) the kernel throws the
following warning on avr32:

WARNING: at 900322e4 [verbose debug info unavailable]
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 3.12.0-rc2 #117
task: 901c3ecc ti: 901c0000 task.ti: 901c0000
PC is at cpu_idle_poll_ctrl+0x1c/0x38
LR is at comparator_mode+0x3e/0x40
pc : [<900322e4>] lr : [<90014882>] Not tainted
sp : 901c1f74 r12: 00000000 r11: 901c74a0
r10: 901d2510 r9 : 00000001 r8 : 901db4de
r7 : 901c74a0 r6 : 00000001 r5 : 00410020 r4 : 901db574
r3 : 00410024 r2 : 90206fe0 r1 : 00000000 r0 : 007f0000
Flags: qvnzc
Mode bits: hjmde....G
CPU Mode: Supervisor
Call trace:
[<90039ede>] clockevents_set_mode+0x16/0x2e
[<90039f00>] clockevents_shutdown+0xa/0x1e
[<9003a078>] clockevents_exchange_device+0x58/0x70
[<9003a78c>] tick_check_new_device+0x38/0x54
[<9003a1a2>] clockevents_register_device+0x32/0x90
[<900035c4>] time_init+0xa8/0x108
[<90000520>] start_kernel+0x128/0x23c

When the 'avr32_comparator' clockevent device is registered,
the clockevent core sets the mode of that clockevent device
to CLOCK_EVT_MODE_SHUTDOWN. Due to this, the 'comparator_mode'
function calls the 'cpu_idle_poll_ctrl' to disables idle poll.
This results in the aforementioned warning because the polling
is not enabled yet.

Change the code to only disable idle poll if it is enabled by
the same function to avoid the warning.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Gabor Juhos <juhosg@xxxxxxxxxxx>
Note: the patch is against v3.12-rc2.
arch/avr32/kernel/time.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/avr32/kernel/time.c b/arch/avr32/kernel/time.c
index 869a1c6..12f828a 100644
--- a/arch/avr32/kernel/time.c
+++ b/arch/avr32/kernel/time.c
@@ -98,7 +98,14 @@ static void comparator_mode(enum clock_event_mode mode,
sysreg_write(COMPARE, 0);
pr_debug("%s: stop\n", evdev->name);
- cpu_idle_poll_ctrl(false);
+ if (evdev->mode == CLOCK_EVT_MODE_ONESHOT ||
+ evdev->mode == CLOCK_EVT_MODE_RESUME) {
+ /*
+ * Only disable idle poll if we have forced that
+ * in a previous call.
+ */
+ cpu_idle_poll_ctrl(false);
+ }
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