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From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: Raphael Poggi <raphael.poggi@lynxleap.co.uk>, qemu-devel@nongnu.org
Cc: luc@lmichel.fr, damien.hedde@dahe.fr,
	Peter Maydell <peter.maydell@linaro.org>
Subject: Re: [PATCH] hw/core/clock: always iterate through childs in clock_propagate_period
Date: Thu, 18 Apr 2024 21:43:42 +0200	[thread overview]
Message-ID: <5b8ce05b-62c6-4362-aa16-a9e845eb4df7@linaro.org> (raw)
In-Reply-To: <20240418191602.2017-1-raphael.poggi@lynxleap.co.uk>

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);
>       }
>   }
>   



  reply	other threads:[~2024-04-18 19:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-18 19:16 [PATCH] hw/core/clock: always iterate through childs in clock_propagate_period Raphael Poggi
2024-04-18 19:43 ` Philippe Mathieu-Daudé [this message]
2024-04-18 20:39   ` Raphael Poggi
2024-04-19 15:08     ` Peter Maydell
2024-04-19 16:08       ` Raphael Poggi
2024-04-19 16:24         ` Peter Maydell
2024-04-19 16:30         ` Philippe Mathieu-Daudé

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