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Date: Thu, 02 Jul 2015 20:43:18 +0300
From: Dmitry Osipenko <digetx@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH v2] arm_mptimer: Fix timer shutdown
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <peter.crosthwaite@xilinx.com>, QEMU Developers <qemu-devel@nongnu.org>

02.07.2015 20:34, Peter Maydell пишет:
> On 2 July 2015 at 18:20, Dmitry Osipenko <digetx@gmail.com> wrote:
>> Timer, running in periodic mode, can't be stopped or coming one-shot tick
>> won't be canceled because timer control code just doesn't handle timer
>> disabling. Fix it by deleting timer if enable bit isn't set.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>
>> v2: Avoid calling timer_del() if the timer was already disabled as per
>>      Peter Maydell suggestion.
>>
>>   hw/timer/arm_mptimer.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/timer/arm_mptimer.c b/hw/timer/arm_mptimer.c
>> index 8b93b3c..51c18de 100644
>> --- a/hw/timer/arm_mptimer.c
>> +++ b/hw/timer/arm_mptimer.c
>> @@ -122,11 +122,17 @@ static void timerblock_write(void *opaque, hwaddr addr,
>>       case 8: /* Control.  */
>>           old = tb->control;
>>           tb->control = value;
>> -        if (((old & 1) == 0) && (value & 1)) {
>> +        if (((old & 1) == 0) && ((value & 1) == 0)) {
>> +            break;
>> +        }
>> +        if (value & 1) {
>>               if (tb->count == 0 && (tb->control & 2)) {
>>                   tb->count = tb->load;
>>               }
>>               timerblock_reload(tb, 1);
>> +        } else {
>> +            /* Shutdown timer.  */
>> +            timer_del(tb->timer);
>
>
> This will now cause us to do the "reload the timer"
> logic if you write a 1 to the control bit when it was
> already 1, which we didn't do before.
>
> The logic I suggested in my previous review
> comment gets this right...
>
> -- PMM
>

Yep, you right. I overlooked it, let me try again.

-- 
Dmitry