Re: [PATCH] hw/char/mchp_pfsoc_mmuart: QOM'ify PolarFire MMUART

[Peter Maydell]

On Thu, 23 Sept 2021 at 11:29, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 9/23/21 07:16, Bin Meng wrote:> On Sun, Sep 19, 2021 at 2:07 AM
> Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> >> +static void mchp_pfsoc_mmuart_realize(DeviceState *dev, Error **errp)
> >> +{
> >> +    MchpPfSoCMMUartState *s = MCHP_PFSOC_UART(dev);
> >> +
> >> +    qdev_prop_set_uint8(DEVICE(&s->serial_mm), "regshift", 2);
> >> +    qdev_prop_set_uint32(DEVICE(&s->serial_mm), "baudbase", 399193);
> >> +    qdev_prop_set_uint8(DEVICE(&s->serial_mm), "endianness",
> >> +                        DEVICE_LITTLE_ENDIAN);
> >
> > It looks like serial_mm_init() does one more thing:
> >
> >      qdev_set_legacy_instance_id(DEVICE(smm), base, 2);
> >
> > I am not sure what that is.
>
> I'll defer on Paolo / Marc-André for that part, I think this is for
> migrating legacy (x86?) machines, which is not the case.

Yes, this is only needed for backwards-compatibility of incoming
migration data with old versions of QEMU which implemented migration
of devices with hand-rolled code. If a device didn't previously
handle migration at all then it should not now be setting the
legacy instance ID.

Speaking of migration, I notice that this QOM conversion does
not add a vmstate, which usually we do as part of the QOM conversion.
The device is also missing a reset method.

thanks
-- PMM