Re: [PATCH v4 18/37] mips: baudbase is 115200 by default

[Philippe Mathieu-Daudé]

On 11/25/19 11:12 AM, Marc-André Lureau wrote:
> Hi
>
> On Mon, Nov 25, 2019 at 2:07 PM Aleksandar Markovic
> <address@hidden> wrote:
> > On Wednesday, November 20, 2019, Marc-André Lureau <address@hidden> wrote:
> > > Signed-off-by: Marc-André Lureau <address@hidden>
> > > ---
> > >   hw/mips/mips_mipssim.c | 1 -
> > >   1 file changed, 1 deletion(-)
> > >
> > > diff --git a/hw/mips/mips_mipssim.c b/hw/mips/mips_mipssim.c
> > > index bfafa4d7e9..3cd0e6eb33 100644
> > > --- a/hw/mips/mips_mipssim.c
> > > +++ b/hw/mips/mips_mipssim.c
> > > @@ -223,7 +223,6 @@ mips_mipssim_init(MachineState *machine)
> > >       if (serial_hd(0)) {
> > >           DeviceState *dev = qdev_create(NULL, TYPE_SERIAL_IO);
> > >
> > > -        qdev_prop_set_uint32(DEVICE(dev), "baudbase", 115200);
> > >           qdev_prop_set_chr(dev, "chardev", serial_hd(0));
> > >           qdev_set_legacy_instance_id(dev, 0x3f8, 2);
> > >           qdev_init_nofail(dev);
> > > --
> >
> >
> > Please mention in your commit message where the default baudbase is set.
>
> ok
>
> > Also, is there a guarantie that default value 115200 will never change in 
> > future?
>
> The level of stability on properties in general is unclear to me.
>
> Given that 115200 is standard for serial, it is unlikely to change
> though.. We can have an assert there instead?
>
> Peter, what do you think? thanks

This property confused me by the past. It is _not_ the baudrate.
It is the input frequency clocking the UART ('XIN' pin, Xtal INput).

Each board has its own frequency, and it can even be variable (the clock 
domain tree can reconfigure it at a different rate).

I'm not sure it makes sense to have a default, and I don't know what is 
the frequency modeled by the SPIM simulator.