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From: Peter Crosthwaite <crosthwaitepeter@gmail.com>
Date: Wed, 6 Jan 2016 04:17:43 -0800
Message-ID: <20160106121743.GD4227@pcrost-box>
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	<efba01ebc3e93fb00993a2de72c7794b5e4e1411.1451960508.git.digetx@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH v8 3/4] hw/ptimer: Update .delta on
	period/freq change
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To: Dmitry Osipenko <digetx@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Peter Crosthwaite <crosthwaitepeter@gmail.com>, qemu-arm@nongnu.org, QEMU Developers <qemu-devel@nongnu.org>

On Tue, Jan 05, 2016 at 05:33:28AM +0300, Dmitry Osipenko wrote:
> Delta value must be updated on period/freq change, otherwise running timer
> would be restarted (counter reloaded with old delta). Only m68k/mcf520x
> and arm/arm_timer devices are currently doing freq change correctly, i.e.
> stopping the timer. Perform delta update to fix affected devices and
> eliminate potential further mistakes.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>

Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>

> ---
>  hw/core/ptimer.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c
> index 96a6c7a..8c2dd9f 100644
> --- a/hw/core/ptimer.c
> +++ b/hw/core/ptimer.c
> @@ -207,6 +207,7 @@ void ptimer_stop(ptimer_state *s)
>  /* Set counter increment interval in nanoseconds.  */
>  void ptimer_set_period(ptimer_state *s, int64_t period)
>  {
> +    s->delta = ptimer_get_count(s);
>      s->period = period;
>      s->period_frac = 0;
>      if (s->enabled) {
> @@ -218,6 +219,7 @@ void ptimer_set_period(ptimer_state *s, int64_t period)
>  /* Set counter frequency in Hz.  */
>  void ptimer_set_freq(ptimer_state *s, uint32_t freq)
>  {
> +    s->delta = ptimer_get_count(s);
>      s->period = 1000000000ll / freq;
>      s->period_frac = (1000000000ll << 32) / freq;
>      if (s->enabled) {
> -- 
> 2.6.4
>