[PATCH v3 5/5] powernv:cpufreq: Implement the driver->get() method

[Viresh Kumar]

On 21 March 2014 16:34, Gautham R Shenoy <ego at linux.vnet.ibm.com> wrote:
> Heh! Well, that wasn't the reason why this was sent out as a separate
> patch, but never mind. Though I don't understand why it would be
> difficult to review the patch though.

Because the initial driver wasn't complete earlier. There were 2-3 patches
after the first one which are changing what the first patch has added.
Nothing else :)

>> > +static void powernv_read_cpu_freq(void *ret_freq)
>> > +{
>> > +       unsigned long pmspr_val;
>> > +       s8 local_pstate_id;
>> > +       int *cur_freq, freq, pstate_id;
>> > +
>> > +       cur_freq = (int *)ret_freq;
>>
>> You don't need cur_freq variable at all..
>
> I don't like it either. But the compiler complains without this hack
> :-(

Why would the compiler warn for doing this?:

*(int *)ret_freq = freq;

>> > +       pmspr_val = get_pmspr(SPRN_PMSR);
>> > +
>> > +       /* The local pstate id corresponds bits 48..55 in the PMSR.
>> > +         * Note: Watch out for the sign! */
>> > +       local_pstate_id = (pmspr_val >> 48) & 0xFF;
>> > +       pstate_id = local_pstate_id;
>>
>> similarly local_pstate_id
>
> well, I am interested in the bits 48..55 of pmspr_val. That's the
> pstate_id which can be negative. So I'll like to keep
> local_pstate_id.

Can you please explain at bit level how getting the value in a s8
first and then into a s32 will help you here? Instead of getting it
directly into s32.