Re: [Qemu-devel] [PATCH v2 3/7] allwinner-a10-pit: avoid generation of spurious interrupts

[Beniamino Galvani]

On Mon, Mar 03, 2014 at 09:08:27PM +1000, Peter Crosthwaite wrote:
> On Mon, Mar 3, 2014 at 12:06 AM, Beniamino Galvani <address@hidden> wrote:
> > The model was generating interrupts for all enabled timers after the
> > expiration of one of them. Avoid this by passing to the timer callback
> > function a structure containing the index of the expired timer.
> >
> 
> Nice catch! I think there was a conditional in the earlier versions of
> the original series that caught this but it got lost in the later
> reivew stages. I do however prefer this de-looped/coreified
> implementation.
> 
> > Signed-off-by: Beniamino Galvani <address@hidden>
> > ---
> >  hw/timer/allwinner-a10-pit.c |   30 +++++++++++++++++++-----------
> >  1 file changed, 19 insertions(+), 11 deletions(-)
> >
> > diff --git a/hw/timer/allwinner-a10-pit.c b/hw/timer/allwinner-a10-pit.c
> > index b27fce8..3e1c183 100644
> > --- a/hw/timer/allwinner-a10-pit.c
> > +++ b/hw/timer/allwinner-a10-pit.c
> > @@ -19,6 +19,11 @@
> >  #include "sysemu/sysemu.h"
> >  #include "hw/timer/allwinner-a10-pit.h"
> >
> > +typedef struct TimerContext {
> > +    AwA10PITState *state;
> 
> "state" is a bit ambiguous for a variable name. I have seen "parent"
> used in this context before (although I must confess that may get
> confused with QOM terms)."container"?

"container" gives me the idea that the TimerContext is a member of the
AwA10PITState struct, which is not the case.

Is "pit_state" better?

> 
> > +    int index;
> > +} TimerContext;
> > +
> >  static uint64_t a10_pit_read(void *opaque, hwaddr offset, unsigned size)
> >  {
> >      AwA10PITState *s = AW_A10_PIT(opaque);
> > @@ -193,18 +198,17 @@ static void a10_pit_reset(DeviceState *dev)
> >
> >  static void a10_pit_timer_cb(void *opaque)
> >  {
> > -    AwA10PITState *s = AW_A10_PIT(opaque);
> > -    uint8_t i;
> > +    TimerContext *tc = opaque;
> > +    AwA10PITState *s = tc->state;
> > +    uint8_t i = tc->index;
> >
> > -    for (i = 0; i < AW_A10_PIT_TIMER_NR; i++) {
> > -        if (s->control[i] & AW_A10_PIT_TIMER_EN) {
> > -            s->irq_status |= 1 << i;
> > -            if (s->control[i] & AW_A10_PIT_TIMER_MODE) {
> > -                ptimer_stop(s->timer[i]);
> > -                s->control[i] &= ~AW_A10_PIT_TIMER_EN;
> > -            }
> > -            qemu_irq_pulse(s->irq[i]);
> > +    if (s->control[i] & AW_A10_PIT_TIMER_EN) {
> > +        s->irq_status |= 1 << i;
> > +        if (s->control[i] & AW_A10_PIT_TIMER_MODE) {
> > +            ptimer_stop(s->timer[i]);
> > +            s->control[i] &= ~AW_A10_PIT_TIMER_EN;
> >          }
> > +        qemu_irq_pulse(s->irq[i]);
> >      }
> >  }
> >
> > @@ -213,6 +217,7 @@ static void a10_pit_init(Object *obj)
> >      AwA10PITState *s = AW_A10_PIT(obj);
> >      SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
> >      QEMUBH * bh[AW_A10_PIT_TIMER_NR];
> > +    TimerContext *tc;
> 
> tc ...
> 
> >      uint8_t i;
> >
> >      for (i = 0; i < AW_A10_PIT_TIMER_NR; i++) {
> > @@ -223,7 +228,10 @@ static void a10_pit_init(Object *obj)
> >      sysbus_init_mmio(sbd, &s->iomem);
> >
> >      for (i = 0; i < AW_A10_PIT_TIMER_NR; i++) {
> 
> ... is a local variable to this for loop iteration. So it can be
> defined here for easier reading.

Ok.

Beniamino

> 
> Otherwise:
> 
> Reviewed-by: Peter Crosthwaite <address@hidden>
> 
> Regards,
> Peter
> 
> > -        bh[i] = qemu_bh_new(a10_pit_timer_cb, s);
> > +        tc = g_malloc(sizeof(TimerContext));
> > +        tc->state = s;
> > +        tc->index = i;
> > +        bh[i] = qemu_bh_new(a10_pit_timer_cb, tc);
> >          s->timer[i] = ptimer_init(bh[i]);
> >          ptimer_set_freq(s->timer[i], 240000);
> >      }
> > --
> > 1.7.10.4
> >
> >