Re: [Qemu-devel] [RFC v1 0/2] ARM MPTimer fixes and refactoring

[Peter Crosthwaite]

On Mon, Oct 5, 2015 at 9:07 AM, Dmitry Osipenko <address@hidden> wrote:
> 03.10.2015 16:11, Dmitry Osipenko пишет:
>
>> 20.09.2015 20:48, Peter Crosthwaite пишет:
>>>
>>> On Sun, Jul 5, 2015 at 1:58 PM, Peter Crosthwaite
>>> <address@hidden> wrote:
>>>>
>>>> On Sun, Jul 5, 2015 at 1:47 PM, Dmitry Osipenko <address@hidden>
>>>> wrote:
>>>>>
>>>>> 05.07.2015 23:26, Peter Crosthwaite пишет:
>>>>>
>>>>>> Hi Dmitry,
>>>>>>
>>>>>> Based on my comment earlier, this is what I came up with RE
>>>>>> consolidation
>>>>>> of
>>>>>> those arm_mptimer code paths that were giving you problems. I have not
>>>>>> done the
>>>>>> interrupt mask fix, as that one from your series is reasonably
>>>>>> independent.
>>>>>>
>>>>>> Regards,
>>>>>> Peter
>>>>>>
>>>>>> Peter Crosthwaite (2):
>>>>>>     timer: arm_mp: Factor out timer value calculation
>>>>>>     timer: arm_mp: consolidate control and counter write logic
>>>>>>
>>>>>>    hw/timer/arm_mptimer.c | 73
>>>>>> +++++++++++++++++++++++++++++---------------------
>>>>>>    1 file changed, 42 insertions(+), 31 deletions(-)
>>>>>>
>>>>>
>>>>> Hi Peter, thanks a lot! Generally, I don't have any trouble with
>>>>> currently
>>>>> missed functionality, just noticed it while was hacking my NVIDIA
>>>>> Tegra2
>>>>> emulation pet-project and decided to contribute =).
>>>>>
>>>>> It looks like you are trying to duplicate what generic ptimer is
>>>>> already
>>>>> doing, isn't it?
>>>>>
>>>>
>>>> Yes, ptimer was probably the correct way to do this in the first
>>>> place. Some of the new code structures introduced in this patch series
>>>> are directly applicable though for that conversion effort.
>>>>
>>>
>>> I looked into doing this with ptimer, and pitmer doesn't really play
>>> nice with periodic down counters. You could do the subtractions
>>> against an up counter with the load value but that seems just as
>>> complex as the current solution IMO. The hardest part is setting the
>>> counter value on an already running timer.
>>>
>>> The alternative is to patch ptimer to handle down timers.
>>>
>>> Regards,
>>> Peter
>>>
>>
>> Hmm, I think you missed something. Ptimer is doing downcount, not up.
>> ptimer_get_count() might be a misnomer, it returns current timer value (it
>> goes
>> down to 0), not a passed ticks count number. Ptimer also should handle
>> reloading
>> of a running timer just fine with ptimer_set_count(), don't see any
>> trouble
>> here. Anyway, I'll try to re-implement MPtimer using ptimer ASAP and see
>> how it
>> really fits.
>>
>
> Finally, I tried ptimer and everything seem to work perfect. Pausing,
> re-loading, etc works as it should. Will send the patch soon.
>

Great!

Thanks for the efforts. I'll take a CC on the review.

Do on the fly prescaler changes work?

Regards,
Peter

> --
> Dmitry