[U-Boot] [PATCH v4 1/3] net: designware: fix descriptor layout and warnings on 64-bit archs

[Marek Vasut <marex@denx.de>]

On 04/17/2016 01:14 PM, Beniamino Galvani wrote:
> On Sun, Apr 17, 2016 at 11:56:58AM +0200, Marek Vasut 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 don't you use u32 instead of ulong ? The u32 is well defined.
>> DTTO all over the place.
> 
> &txbuffs[idx * CONFIG_ETH_BUFSIZE] is a pointer (and hence has the
> size of a ulong) and casting it to u32 would give a warning on 64 bit
> archs ("cast from pointer to integer of different size").

Will cast to uintptr_t and then to u32 help ?

It's just a feeling, but casting to ulong just to circumvent compiler
warning does not sound right.

>> btw just curious, but what will happen if the descriptors get allocated
>> in area above 4GiB ? Will the code silently corrupt memory by discarding
>> the top bits in the descriptor pointer?
> 
> No, if the driver private structure (which contains buffers and
> descriptors) is above 4GiB, designware_initialize() will complain and
> return an error.

Which code checks that ?

> Beniamino
> 


-- 
Best regards,
Marek Vasut