Re: [PATCH] hw/i2c/mpc_i2c.c: Fix mmio region size

[BALATON Zoltan]

On Mon, 22 Jul 2024, Philippe Mathieu-Daudé wrote:
> +Amit & Andrew
>
> On 22/7/24 00:55, BALATON Zoltan wrote:
> > The last register of this device is at offset 0x14 occupying 8 bits so
> > to cover it the mmio region needs to be 0x15 bytes long. Also correct
> > the name of the field storing this register value to match the
> > register name.
> >
> > Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> > ---
> >   hw/i2c/mpc_i2c.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
>
>
> > @@ -329,7 +329,7 @@ static void mpc_i2c_realize(DeviceState *dev, Error 
> > **errp)
> >       MPCI2CState  *i2c = MPC_I2C(dev);
> >       sysbus_init_irq(SYS_BUS_DEVICE(dev), &i2c->irq);
> >       memory_region_init_io(&i2c->iomem, OBJECT(i2c), &i2c_ops, i2c,
> > -                          "mpc-i2c", 0x14);
> > +                          "mpc-i2c", 0x15);
>
> Personally I'm not a big fan of non-pow2 regions, so I'd have picked
> 0x20 or 0x100 where the 2nd i2c controller starts. Amit, what do you

Coverung unused areas isn't a good idea because that would omit invalid 
read/write warnings when those are enabled so it's harder to catch 
unimplemented registers that way. So 0x100 is definitely overkill, 0x20 
could be acceptable as other regs are also covering some unused area after 
them but is also unnecessary when we can cover exactly the area where the 
register is.

Regards,
BALATON Zoltan

> think?
>
> Anyhow,
>
> Fixes: 7abb479c7a ("PPC: E500: Add FSL I2C controller")
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
> >       sysbus_init_mmio(SYS_BUS_DEVICE(dev), &i2c->iomem);
> >       i2c->bus = i2c_init_bus(dev, "i2c");
> >   }