Re: [PATCH v2 03/11] goldfish_rtc: Add endianness property

[Laurent Vivier]

On 04/07/2022 11:59, Richard Henderson wrote:
> On 7/4/22 02:58, Stafford Horne wrote:
> > -static const MemoryRegionOps goldfish_rtc_ops = {
> > -    .read = goldfish_rtc_read,
> > -    .write = goldfish_rtc_write,
> > -    .endianness = DEVICE_NATIVE_ENDIAN,
> > -    .valid = {
> > -        .min_access_size = 4,
> > -        .max_access_size = 4
> > -    }
> > +static const MemoryRegionOps goldfish_rtc_ops[3] = {
> > +    [DEVICE_NATIVE_ENDIAN] = {
> > +        .read = goldfish_rtc_read,
> > +        .write = goldfish_rtc_write,
> > +        .endianness = DEVICE_NATIVE_ENDIAN,
> > +        .valid = {
> > +            .min_access_size = 4,
> > +            .max_access_size = 4
> > +        }
> > +    },
> > +    [DEVICE_LITTLE_ENDIAN] = {
> > +        .read = goldfish_rtc_read,
> > +        .write = goldfish_rtc_write,
> > +        .endianness = DEVICE_LITTLE_ENDIAN,
> > +        .valid = {
> > +            .min_access_size = 4,
> > +            .max_access_size = 4
> > +        }
> > +    },
> > +    [DEVICE_BIG_ENDIAN] = {
> > +        .read = goldfish_rtc_read,
> > +        .write = goldfish_rtc_write,
> > +        .endianness = DEVICE_BIG_ENDIAN,
> > +        .valid = {
> > +            .min_access_size = 4,
> > +            .max_access_size = 4
> > +        }
> > +    },
> >   };
>
> You don't need 3 copies, only big and little.
>
> > +static Property goldfish_rtc_properties[] = {
> > +    DEFINE_PROP_UINT8("endianness", GoldfishRTCState, endianness,
> > +                      DEVICE_NATIVE_ENDIAN),
> > +    DEFINE_PROP_END_OF_LIST(),
> > +};
>
> ... and I think the clear desire for default is little-endian.  I would make the property 
> be bool, and add a comment that this is only for m68k compatibility, so don't use it in 
> new code.

m68k doesn't really need this.

kernel with the m68k virt machine and goldfish device supports "native" mode so I think 
it's not needed to add another layer of complexity for it.

Thanks,
Laurent