[U-Boot] [PATCH v2] timer: add High Precision Event Timers (HPET) support

[Andy Shevchenko]

On Wed, Apr 4, 2018 at 7:40 AM, Ivan Gorinov <ivan.gorinov at intel.com> wrote:
> On Wed, Apr 04, 2018 at 12:15:24PM +0800, Bin Meng wrote:
>> > Doesn't readX/writeX imply a single I/O operation?
>> > It may be misleading to define it as two.
>> >
>> > Assuming MMX or SSE2 to be supported by all x86 processors, 64-bit I/O
>> > registers can be accessed as a single operation even in 32-bit code:
>> >
>>
>> Adding such requirement (MMX or SSE2) to U-Boot is not good. Why do we
>> require MMX or SSE2 for readq? Can we use general purpose registers?
>
> In 32-bit code, we can't make a 64-bit memory read operation using only
> general purpose registers.

Exactly, that's why you have to use non-atomic variants.

-- 
With Best Regards,
Andy Shevchenko