Re: [Qemu-devel] [PATCH v11 7/7] arm_mptimer: Convert to use ptimer

[Dmitry Osipenko <digetx@gmail.com>]

24.01.2016 17:59, Dmitry Osipenko пишет:
> Hello Peter,
>
> 24.01.2016 08:25, Peter Crosthwaite пишет:
>
> [snip]
>
>>> +        timerblock_run(tb->timer, control, (value != 0) && (control & 1));
>>>           break;
>>>       case 8: /* Control.  */
>>> -        old = tb->control;
>>> -        tb->control = value;
>>> -        if (value & 1) {
>>> -            if ((old & 1) && (tb->count != 0)) {
>>> -                /* Do nothing if timer is ticking right now.  */
>>> -                break;
>>> +        if ((value & 1) && (control & 3) != (value & 3)) {
>>> +            uint64_t count = (value & 0xff00) ? 1 :
>>> ptimer_get_count(tb->timer);
>>> +            if ((count == 0) && (value & 2)) {
>>> +                timerblock_set_count(tb->timer, value, &count);
>>
>> This looks like a weird corner-case, what does it do exactly? I can't
>> follow it so it needs a comment :)
>>
>
> It does the following:
>
> mode     | prescaler | reload if counter == 0 | tick immediately if counter == 0
> --------------------------------------------------------------------------------
> oneshot         == 0               0                         0
> oneshot      != 0               0                         1
> periodic     == 0               1                         0
> periodic     != 0               0                         1
>
> If writing control register with prescaler = 0, then for one-shot timer with
> counter == 0 or periodic timer with load = counter == 0 this is NOP. Will add a
> comment.
>
> Thanks for review!
>

Just realized that I missed timer re-run on prescaler change. So it was a good 
question! =)

-- 
Dmitry