Re: [PATCH 11/14] ppc/pnv: Compute the PHB index from the PHB4 PEC model

[Cédric Le Goater]

On 12/7/21 11:06, Frederic Barrat wrote:
> On 02/12/2021 15:42, Cédric Le Goater wrote:
> > Use the num_stacks class attribute to compute the PHB index depending
> > on the PEC index :
> >
> >    * PEC0 provides 1 PHB  (PHB0)
> >    * PEC1 provides 2 PHBs (PHB1 and PHB2)
> >    * PEC2 provides 3 PHBs (PHB3, PHB4 and PHB5)
> >
> > Signed-off-by: Cédric Le Goater <clg@kaod.org>
> > ---
> >   hw/pci-host/pnv_phb4_pec.c | 16 ++++++++++++++++
> >   hw/ppc/pnv.c               |  4 +---
> >   2 files changed, 17 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/pci-host/pnv_phb4_pec.c b/hw/pci-host/pnv_phb4_pec.c
> > index 293909b5cb90..a7dd4173d598 100644
> > --- a/hw/pci-host/pnv_phb4_pec.c
> > +++ b/hw/pci-host/pnv_phb4_pec.c
> > @@ -374,6 +374,19 @@ static void pnv_pec_instance_init(Object *obj)
> >       }
> >   }
> > +static int pnv_pec_phb_offset(PnvPhb4PecState *pec)
> > +{
> > +    PnvPhb4PecClass *pecc = PNV_PHB4_PEC_GET_CLASS(pec);
> > +    int index = pec->index;
> > +    int offset = 0;
> > +
> > +    while (index--) {
> > +        offset += pecc->num_stacks[index];
> > +    }
> > +
> > +    return offset;
> > +}
> > +
>
>
> That seems overly complicated to me and not very readable. The log message is a 
> lot more clear. I'd prefer we have a switch() statement returning the base PHB 
> ID based on the PEC index.

yes I agree but PHB5 is on its way and this is compatible. See :

  
https://github.com/legoater/qemu/commit/d7caa1b74f3f8a90815fa086b87a1bd467b7c988

I will take any good idea fitting both :)

Thanks,

C.

>    Fred
>
>
>
> >   static void pnv_pec_realize(DeviceState *dev, Error **errp)
> >   {
> >       PnvPhb4PecState *pec = PNV_PHB4_PEC(dev);
> > @@ -394,8 +407,10 @@ static void pnv_pec_realize(DeviceState *dev, Error **errp)
> >       for (i = 0; i < pec->num_stacks; i++) {
> >           PnvPhb4PecStack *stack = &pec->stacks[i];
> >           Object *stk_obj = OBJECT(stack);
> > +        int phb_id = pnv_pec_phb_offset(pec) + i;
> >           object_property_set_int(stk_obj, "stack-no", i, &error_abort);
> > +        object_property_set_int(stk_obj, "phb-id", phb_id, &error_abort);
> >           object_property_set_link(stk_obj, "pec", OBJECT(pec), &error_abort);
> >           if (!qdev_realize(DEVICE(stk_obj), NULL, errp)) {
> >               return;
> > @@ -538,6 +553,7 @@ static void pnv_pec_stk_instance_init(Object *obj)
> >       PnvPhb4PecStack *stack = PNV_PHB4_PEC_STACK(obj);
> >       object_initialize_child(obj, "phb", &stack->phb, TYPE_PNV_PHB4);
> > +    object_property_add_alias(obj, "phb-id", OBJECT(&stack->phb), "index");
> >   }
> >   static void pnv_pec_stk_realize(DeviceState *dev, Error **errp)
> > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
> > index 957f0bdfaa6b..f8b0b2a28383 100644
> > --- a/hw/ppc/pnv.c
> > +++ b/hw/ppc/pnv.c
> > @@ -1371,7 +1371,6 @@ static void pnv_chip_power9_phb_realize(PnvChip *chip, 
> > Error **errp)
> >   {
> >       Pnv9Chip *chip9 = PNV9_CHIP(chip);
> >       int i, j;
> > -    int phb_id = 0;
> >       for (i = 0; i < chip->num_pecs; i++) {
> >           PnvPhb4PecState *pec = &chip9->pecs[i];
> > @@ -1396,11 +1395,10 @@ static void pnv_chip_power9_phb_realize(PnvChip *chip, 
> > Error **errp)
> >           pnv_xscom_add_subregion(chip, pec_nest_base, &pec->nest_regs_mr);
> >           pnv_xscom_add_subregion(chip, pec_pci_base, &pec->pci_regs_mr);
> > -        for (j = 0; j < pec->num_stacks; j++, phb_id++) {
> > +        for (j = 0; j < pec->num_stacks; j++) {
> >               PnvPhb4PecStack *stack = &pec->stacks[j];
> >               Object *obj = OBJECT(&stack->phb);
> > -            object_property_set_int(obj, "index", phb_id, &error_fatal);
> >               object_property_set_int(obj, "chip-id", chip->chip_id,
> >                                       &error_fatal);
> >               object_property_set_int(obj, "version", pecc->version,