Re: [Qemu-arm] [Qemu-devel] [PATCH v2] hw/ptimer: Don't wrap around counter for expired timer that uses tick handler

[Mark Cave-Ayland]

On 25/06/16 13:35, Dmitry Osipenko wrote:

> Software should see timer counter wrap around only after IRQ being triggered.
> Change returned counter value to "1" for the expired timer and avoid returning
> wrapped around counter value in periodic mode for the timer that has bottom-half
> handler setup, assuming it drives timer IRQ.
>
> This fixes regression introduced by the commit 5a50307 ("hw/ptimer: Perform
> counter wrap around if timer already expired") on SPARC emulated machine as
> reported by Mark Cave-Ayland.
>
> Signed-off-by: Dmitry Osipenko <address@hidden>
> ---
>  hw/core/ptimer.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c
> index 05b0c27..8006442 100644
> --- a/hw/core/ptimer.c
> +++ b/hw/core/ptimer.c
> @@ -93,10 +93,10 @@ uint64_t ptimer_get_count(ptimer_state *s)
>          bool oneshot = (s->enabled == 2);
>
>          /* Figure out the current counter value.  */
> -        if (s->period == 0 || (expired && (oneshot || use_icount))) {
> +        if (expired && (oneshot || use_icount || s->bh != NULL)) {
>              /* Prevent timer underflowing if it should already have
>                 triggered.  */
> -            counter = 0;
> +            counter = 1;
>          } else {
>              uint64_t rem;
>              uint64_t div;
> @@ -143,7 +143,9 @@ uint64_t ptimer_get_count(ptimer_state *s)
>
>              if (expired && counter != 0) {
>                  /* Wrap around periodic counter.  */
> -                counter = s->limit - (counter - 1) % s->limit;
> +                counter = s->delta = s->limit - (counter - 1) % s->limit;
> +                /* Re-arm timer according to the wrapped around value.  */
> +                ptimer_reload(s);
>              }
>          }
>      } else {

Hi Dmitry,

I ran through all of my OpenBIOS test images for qemu-system-sparc and 
AFAICT this fixes the issue without introducing any further regressions so:

Tested-by: Mark Cave-Ayland <address@hidden>


Many thanks,

Mark.