Around Wed 25 Sep 2013 11:31:19 +0200 or thereabout, Gabor Juhos wrote:
> 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.
Thank you for fixing.
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gabor Juhos <juhosg@xxxxxxxxxxx>
Acked-by: Hans-Christian Egtvedt <egtvedt@xxxxxxxxxxxx>
> ---
> Note: the patch is against v3.12-rc2.
> ---
I'll add this to my for-linus branch, which I'll send a pull request for
soon.
> 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,
> case CLOCK_EVT_MODE_SHUTDOWN:
> 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);
> + }
> break;
> default:
> BUG();
--
mvh
Hans-Christian Egtvedt
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