Re: [Qemu-devel] [PATCH 2/3] arm_mptimer: Fix ONE-SHOT -> PERIODIC mode change

[Peter Crosthwaite]

On Thu, Jul 2, 2015 at 3:52 PM, Dmitry Osipenko <address@hidden> wrote:
> Timer won't start periodic ticking if ONE-SHOT -> PERIODIC mode change 
> happened
> after one-shot tick was completed. Fix it by starting ticking only if timer 
> was
> disabled previously and isn't ticking right now.
>
> Signed-off-by: Dmitry Osipenko <address@hidden>
> ---
>  hw/timer/arm_mptimer.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/hw/timer/arm_mptimer.c b/hw/timer/arm_mptimer.c
> index e230063..58e17c4 100644
> --- a/hw/timer/arm_mptimer.c
> +++ b/hw/timer/arm_mptimer.c
> @@ -122,11 +122,16 @@ static void timerblock_write(void *opaque, hwaddr addr,
>      case 8: /* Control.  */
>          old = tb->control;
>          tb->control = value;
> -        if ((old & 1) == (value & 1)) {
> +        /* Don't do anything if timer already disabled.  */
> +        if (((old & 1) == 0) && ((value & 1) == 0)) {

Your do-nothing code paths are now inconsistent between the 0 and 1
cases. I think this if can be consolidated with:

if (value & 1) {
    if ((old & 1) && (tb->count != 0)) {
        break;
    }
    if (tb->control & 2) {
        ...
    }
    tb_reload();
} else if (old & 1) {
    timer_del();
}
break;

I think it's ok to squash patches 1 and 2. and just make a note in the
commit message of the multiple issues. It's hard to split this without
churning.

>              break;
>          }
>          if (value & 1) {
> -            if (tb->count == 0 && (tb->control & 2)) {
> +            /* Don't do anything if timer already ticking.  */
> +            if (((old & 1) != 0) && (tb->count != 0)) {
> +                break;
> +            }
> +            if (tb->control & 2) {

You have dropped the tb->count == 0 which looks like another bugfix
again. It looks like you are making sure the load value is loaded
regardless of timer run-state. If this is correct it just needs a note
in commit message.

Regards,
Peter

>                  tb->count = tb->load;
>              }
>              timerblock_reload(tb, 1);
> --
> 2.4.4
>
>