[U-Boot] [PATCH v5 2/4] net: designware: fix descriptor layout and warnings on 64-bit archs

[Joe Hershberger]

On Mon, Apr 25, 2016 at 3:17 PM, Beniamino Galvani <b.galvani at gmail.com> wrote:
> On Mon, Apr 25, 2016 at 01:01:10PM -0500, Joe Hershberger wrote:
>> > -               desc_p->dmamac_addr = &txbuffs[idx * CONFIG_ETH_BUFSIZE];
>> > -               desc_p->dmamac_next = &desc_table_p[idx + 1];
>> > +               desc_p->dmamac_addr = (ulong)&txbuffs[idx * CONFIG_ETH_BUFSIZE];
>> > +               desc_p->dmamac_next = (ulong)&desc_table_p[idx + 1];
>>
>> Why are you not casting to the type of the struct member (u32)? Won't
>> this emit warnings on 64-bit?
>
> Hi,
>
> casting to u32 would cause a warning on arm64 ("warning: cast from
> pointer to integer of different size [-Wpointer-to-int-cast]") because
> the pointer is 64bit.
>
> The (ulong) cast is needed to convert the pointer to an arithmetic
> type of same width, which then can be assigned to the struct
> member. The assignment operator implicitly converts between different
> arithmetic types without the need for explicit casts.

That's the part that surprises me. I thought arithmetic assignments
from larger to smaller types would warn.

Anyway, if it's warning clean,

Acked-by: Joe Hershberger <joe.hershberger at ni.com>