Re: [for-8.0] hw/i2c/allwinner-i2c: Fix subclassing of TYPE_AW_I2C_SUN6I

[Thomas Huth <thuth@redhat.com>]

On 11/04/2023 12.31, Peter Maydell wrote:
> In commit 8461bfdca9c we added the TYPE_AW_I2C_SUN6I, which is a
> minor variant of the TYPE_AW_I2C device.  However, we didn't quite
> get the class hierarchy right.  We made the new TYPE_AW_I2C_SUN6I a
> subclass of TYPE_SYS_BUS_DEVICE, which means that you can't validly
> use a pointer to this object via the AW_I2C() cast macro, which
> insists on having something that is an instance of TYPE_AW_I2C or
> some subclass of that type.
> 
> This only causes a problem if QOM cast macro debugging is enabled;
> that is supposed to be on by default, but a mistake in the meson
> conversion in commit c55cf6ab03f4c meant that it ended up disabled by
> default, and we didn't catch this bug.
> 
> Fix the problem by arranging the classes in the same way we do for
> TYPE_PL011 and TYPE_PL011_LUMINARY in hw/char/pl011.c -- make the
> variant class be a subclass of the "normal" version of the device.
> 
> This was reported in
> https://gitlab.com/qemu-project/qemu/-/issues/1586 but this fix alone
> isn't sufficient, as there is a separate cast-related issue in the
> CXL code in pci_expander_bridge.c.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/i2c/allwinner-i2c.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/hw/i2c/allwinner-i2c.c b/hw/i2c/allwinner-i2c.c
> index f24c3ac6f0c..9e8efa1d63f 100644
> --- a/hw/i2c/allwinner-i2c.c
> +++ b/hw/i2c/allwinner-i2c.c
> @@ -466,10 +466,8 @@ static void allwinner_i2c_sun6i_init(Object *obj)
>   
>   static const TypeInfo allwinner_i2c_sun6i_type_info = {
>       .name = TYPE_AW_I2C_SUN6I,
> -    .parent = TYPE_SYS_BUS_DEVICE,
> -    .instance_size = sizeof(AWI2CState),
> +    .parent = TYPE_AW_I2C,
>       .instance_init = allwinner_i2c_sun6i_init,
> -    .class_init = allwinner_i2c_class_init,
>   };
>   
>   static void allwinner_i2c_register_types(void)

Reviewed-by: Thomas Huth <thuth@redhat.com>