[Skiboot] [PATCH v2 2/6] VAS: Initialize the basic VAS internal registers

[Oliver O'Halloran]

On Thu, Nov 24, 2016 at 4:22 AM, Sukadev Bhattiprolu
<sukadev at linux.vnet.ibm.com> wrote:
> Oliver O'Halloran [oohall at gmail.com] wrote:
>> > +
>> > +       for (reg = 0; reg < nregs; reg++) {
>> > +               if (!((valid_wcm_mask >> reg) & 0x1))
>> > +                       continue;
>> > +
>> > +               *(window_start + reg) = 0x0ULL;
>>
>> Is it safe to access these MMIO registers with cached loads/stores?
>
> I am not sure. Please let me know of a safer/better way to do this.

You probably want to use out_be64() and friends from io.h. They use
the real-mode cache inhibited load and store instructions so they
should be safe for accessing MMIO registers.