Re: [PATCH v2 1/3] io-64-nonatomic: add io{read|write}64[be] macros

[Logan Gunthorpe]

On 28/06/17 04:11 AM, Arnd Bergmann wrote:
> This is wrong since ioread* is not the same read* on x86 and other
> architectures that have native PCI PIO accessors, or that require
> additional barriers for those.
> 
> You have to copy hi_lo_readq() here, and call ioread32 twice instead
> of calling readl() twice. Same for iowrite64.
> 
>> +#ifndef ioread64be
>> +#define ioread64be(p) be64_to_cpu(ioread64(p))
>> +#endif
> 
> This has another problem: ioread64() is defined to access little-endian
> registers, just like readq(). This means that instead of be64_to_cpu()
> you need swab64() and always perform the byte swap, otherwise this
> would be broken on big-endian architectures.

Ah, ok, understood. I'll see if I can fix both these issues.

Thanks,

Logan