Re: [PATCH] mos6522: update counters when timer interrupts are off

From: David Gibson <david@gibson.dropbear.id.au>
To: Laurent Vivier <laurent@vivier.eu>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
	qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
	Andrew Randrianasulu <randrianasulu@gmail.com>
Subject: Re: [PATCH] mos6522: update counters when timer interrupts are off
Date: Tue, 26 Nov 2019 10:12:17 +1100	[thread overview]
Message-ID: <20191125231217.GI5582@umbus.fritz.box> (raw)
In-Reply-To: <20191125141414.5015-1-laurent@vivier.eu>

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On Mon, Nov 25, 2019 at 03:14:14PM +0100, Laurent Vivier wrote:
> Even if the interrupts are off, counters must be updated because
> they are running anyway and kernel can try to read them
> (it's the case with g3beige kernel).
> 
> Reported-by: Andrew Randrianasulu <randrianasulu@gmail.com>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>

Applied to ppc-for-4.2, thanks.

> ---
>  hw/misc/mos6522.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/misc/mos6522.c b/hw/misc/mos6522.c
> index aa3bfe1afd..cecf0be59e 100644
> --- a/hw/misc/mos6522.c
> +++ b/hw/misc/mos6522.c
> @@ -113,6 +113,10 @@ static int64_t get_next_irq_time(MOS6522State *s, MOS6522Timer *ti,
>      int64_t d, next_time;
>      unsigned int counter;
>  
> +    if (ti->frequency == 0) {
> +        return INT64_MAX;
> +    }
> +
>      /* current counter value */
>      d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ti->load_time,
>                   ti->frequency, NANOSECONDS_PER_SECOND);
> @@ -149,10 +153,10 @@ static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
>      if (!ti->timer) {
>          return;
>      }
> +    ti->next_irq_time = get_next_irq_time(s, ti, current_time);
>      if ((s->ier & T1_INT) == 0 || (s->acr & T1MODE) != T1MODE_CONT) {
>          timer_del(ti->timer);
>      } else {
> -        ti->next_irq_time = get_next_irq_time(s, ti, current_time);
>          timer_mod(ti->timer, ti->next_irq_time);
>      }
>  }
> @@ -163,10 +167,10 @@ static void mos6522_timer2_update(MOS6522State *s, MOS6522Timer *ti,
>      if (!ti->timer) {
>          return;
>      }
> +    ti->next_irq_time = get_next_irq_time(s, ti, current_time);
>      if ((s->ier & T2_INT) == 0) {
>          timer_del(ti->timer);
>      } else {
> -        ti->next_irq_time = get_next_irq_time(s, ti, current_time);
>          timer_mod(ti->timer, ti->next_irq_time);
>      }
>  }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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