Re: [PATCH] hw/core/clock: always iterate through childs in clock_propagate_period

[Philippe Mathieu-Daudé]

Hi Raphael,

On 18/4/24 21:16, Raphael Poggi wrote:
> When dealing with few clocks depending with each others, sometimes
> we might only want to update the multiplier/diviser on a specific clock
> (cf clockB in drawing below) and call "clock_propagate(clockA)" to
> update the childs period according to the potential new multiplier/diviser 
> values.
>
> +--------+     +--------+      +--------+
> | clockA | --> | clockB |  --> | clockC |
> +--------+     +--------+      +--------+
>
> The actual code would not allow that because, since we cannot call
> "clock_propagate" directly on a child, it would exit on the
> first child has the period has not changed for clockB, only clockC is

Typo "as the period has not changed"?

Why can't you call clock_propagate() on a child?

> impacted in our example.
>
> Signed-off-by: Raphael Poggi <raphael.poggi@lynxleap.co.uk>
> ---
>   hw/core/clock.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/core/clock.c b/hw/core/clock.c
> index a19c7db7df..85421f8b55 100644
> --- a/hw/core/clock.c
> +++ b/hw/core/clock.c
> @@ -101,8 +101,9 @@ static void clock_propagate_period(Clock *clk, bool 
> call_callbacks)
>               if (call_callbacks) {
>                   clock_call_callback(child, ClockUpdate);
>               }
> -            clock_propagate_period(child, call_callbacks);
>           }
> +
> +        clock_propagate_period(child, call_callbacks);
>       }
>   }
>