On Fri, Mar 21, 2014 at 03:01:29PM +0530, Viresh Kumar wrote:
> On Thu, Mar 20, 2014 at 5:41 PM, Gautham R. Shenoy
> <e...@linux.vnet.ibm.com> wrote:
> > From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com>
> >
> > The current frequency of a cpu is reported through the sysfs file
> > cpuinfo_cur_freq. This requires the driver to implement a
> > "->get(unsigned int cpu)" method which will return the current
> > operating frequency.
> >
> > Implement a function named powernv_cpufreq_get() which reads the local
> > pstate from the PMSR and returns the corresponding frequency.
> >
> > Set the powernv_cpufreq_driver.get hook to powernv_cpufreq_get().
> >
> > Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
> > ---
> > drivers/cpufreq/powernv-cpufreq.c | 38
> > ++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 38 insertions(+)
>
> Please merge these fixups with the first patch which is creating the driver.
> I understand that a different guy has created this patch and so wanted
> to have a patch on his name but its really difficult to review this
way.
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.
> Better add your signed-off in the first patch instead. Sending such changes
> once the driver is mainlined looks fine.
Sure, this makes sense.
>
> > diff --git a/drivers/cpufreq/powernv-cpufreq.c
> > b/drivers/cpufreq/powernv-cpufreq.c
> > index 46bee8a..ef6ed8c 100644
> > --- a/drivers/cpufreq/powernv-cpufreq.c
> > +++ b/drivers/cpufreq/powernv-cpufreq.c
> > @@ -206,6 +206,43 @@ static inline void set_pmspr(unsigned long sprn,
> > unsigned long val)
> > BUG();
> > }
> >
> > +/*
> > + * Computes the current frequency on this cpu
> > + * and stores the result in *ret_freq.
> > + */
> > +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
:-(
>
> > + 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.
>
> > +
> > + freq = pstate_id_to_freq(pstate_id);
> > + pr_debug("cpu %d pmsr %lx pstate_id %d frequency %d \n",
> > + smp_processor_id(), pmspr_val, pstate_id, freq);
> > + *cur_freq = freq;
>
> Move above print here after a blank line. Also remove freq variable as
> well and use *cur_freq directly.. And then you can rename it to freq
as well.
We can get rid of freq and use *cur_freq in its place.
Thanks for the detailed review.
--
Regards
gautham.
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