linux-kernel - Re: [PATCH v3 2/3] cpuidle:powernv: Add helper function to populate powernv idle states.

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Message-Id: <20161129060911.GA30454@in.ibm.com>
Date:   Tue, 29 Nov 2016 11:39:11 +0530
From:   Gautham R Shenoy <ego@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michael Neuling <mikey@...ling.org>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        "Shreyas B. Prabhu" <shreyasbp@...il.com>,
        Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
        Stewart Smith <stewart@...ux.vnet.ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        "Oliver O'Halloran" <oohall@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, skiboot@...ts.ozlabs.org
Subject: Re: [PATCH v3 2/3] cpuidle:powernv: Add helper function to populate
 powernv idle states.

Hi Michael,

On Wed, Nov 23, 2016 at 08:49:08PM +1100, Michael Ellerman wrote:
> "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com> writes:
> 
> > diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
> > index 7fe442c..9240e08 100644
> > --- a/drivers/cpuidle/cpuidle-powernv.c
> > +++ b/drivers/cpuidle/cpuidle-powernv.c
> > @@ -243,28 +262,31 @@ static int powernv_add_idle_states(void)
> >  		 */
> >  		if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
> >  			continue;
> > +		/*
> > +		 * Firmware passes residency and latency values in ns.
> > +		 * cpuidle expects it in us.
> > +		 */
> > +		exit_latency = ((unsigned int)latency_ns[i]) / 1000;
> > +		target_residency = (!rc) ? ((unsigned int)residency_ns[i]) : 0;
> > +		target_residency /= 1000;
> 
> Urk.
> 
> Can you just do it normally:
> 
> 		if (rc == 0)
> 			target_residency = (unsigned int)residency_ns[i] / 1000;

Wrote this in a non-standard manner since the normal way would exceed
80 chars.

> 
> I also don't see why you need the cast?

It is a remnant from the previous code. But I see your point, the cast
is redundant, and removing it will make it possible to implement this
in the normal manner without checkpatch warning about it.

> 
> cheers
> 

--
Thanks and Regards
gautham.