Re: [Qemu-devel] [PATCH] hw/char/cmsdk-apb-timer: Correctly identify and set one-shot mode

[Peter Maydell]

On 19 June 2018 at 03:08, Guenter Roeck <address@hidden> wrote:
> The CMSDK APB timer is currently always configured as periodic timer.
> This results in the following messages when trying to boot Linux.
>
> Timer with delta zero, disabling
>
> If the timer limit set with the RELOAD command is 0, the timer
> needs to be enabled as one-shot timer.
>
> Signed-off-by: Guenter Roeck <address@hidden>
> ---
>  hw/timer/cmsdk-apb-timer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/timer/cmsdk-apb-timer.c b/hw/timer/cmsdk-apb-timer.c
> index 9878746..79c1b49 100644
> --- a/hw/timer/cmsdk-apb-timer.c
> +++ b/hw/timer/cmsdk-apb-timer.c
> @@ -119,7 +119,7 @@ static void cmsdk_apb_timer_write(void *opaque, hwaddr 
> offset, uint64_t value,
>          }
>          s->ctrl = value & 0xf;
>          if (s->ctrl & R_CTRL_EN_MASK) {
> -            ptimer_run(s->timer, 0);
> +            ptimer_run(s->timer, ptimer_get_limit(s->timer) == 0);
>          } else {
>              ptimer_stop(s->timer);
>          }
> --
> 2.7.4

Thanks for this patch. I was wondering whether it would be better
just to remove the fprintf message instead. I'll either apply
this or send a patch to do that before 3.0, anyway.

I think we also want to make sure we convert back to a
periodic timer if the reload register is written with a nonzero
value before the timer expires (and that if that happens after
the timer expired that we restart the timer). Thinking about
this is also on my todo list.

-- PMM