RE: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver

From: <ilialin@codeaurora.org>
To: 'Viresh Kumar' <viresh.kumar@linaro.org>,
	'Amit Kucheria' <amit.kucheria@linaro.org>
Cc: 'Michael Turquette' <mturquette@baylibre.com>,
	sboyd@kernel.org, 'Rob Herring' <robh@kernel.org>,
	'Mark Rutland' <mark.rutland@arm.com>,
	nm@ti.com, lgirdwood@gmail.com, broonie@kernel.org,
	'Andy Gross' <andy.gross@linaro.org>,
	'David Brown' <david.brown@linaro.org>,
	catalin.marinas@arm.com, will.deacon@arm.com,
	"'Rafael J. Wysocki'" <rjw@rjwysocki.net>,
	linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
	'LKML' <linux-kernel@vger.kernel.org>,
	'Linux PM list' <linux-pm@vger.kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
	'lakml' <linux-arm-kernel@lists.infradead.org>,
	'Rajendra Nayak' <rnayak@codeaurora.org>,
	nicolas.dechesne@linaro.org, celster@codeaurora.org,
	tfinkel@codeaurora.org
Subject: RE: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver
Date: Thu, 17 May 2018 10:50:34 +0300	[thread overview]
Message-ID: <017601d3edb3$c0d96d40$428c47c0$@codeaurora.org> (raw)
In-Reply-To: <20180516141132.aqjif7d5motmmnlo@vireshk-i7>

> -----Original Message-----
> From: Viresh Kumar <viresh.kumar@linaro.org>
> Sent: Wednesday, May 16, 2018 17:12
> To: Amit Kucheria <amit.kucheria@linaro.org>
> Cc: Ilia Lin <ilialin@codeaurora.org>; Michael Turquette
> <mturquette@baylibre.com>; sboyd@kernel.org; Rob Herring
> <robh@kernel.org>; Mark Rutland <mark.rutland@arm.com>; nm@ti.com;
> lgirdwood@gmail.com; broonie@kernel.org; Andy Gross
> <andy.gross@linaro.org>; David Brown <david.brown@linaro.org>;
> catalin.marinas@arm.com; will.deacon@arm.com; Rafael J. Wysocki
> <rjw@rjwysocki.net>; linux-clk@vger.kernel.org;
> devicetree@vger.kernel.org; LKML <linux-kernel@vger.kernel.org>; Linux
> PM list <linux-pm@vger.kernel.org>; linux-arm-msm@vger.kernel.org; linux-
> soc@vger.kernel.org; lakml <linux-arm-kernel@lists.infradead.org>;
> Rajendra Nayak <rnayak@codeaurora.org>; nicolas.dechesne@linaro.org;
> celster@codeaurora.org; tfinkel@codeaurora.org
> Subject: Re: [PATCH v7 12/14] cpufreq: Add Kryo CPU scaling driver
> 
> On 16-05-18, 16:12, Amit Kucheria wrote:
> > > +       ret = PTR_ERR_OR_ZERO(opp_temp =
> > > +
> dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
> > > +       if (0 > ret)
> >
> > Any particular reason to prefer this over (ret < 0) that is generally
> > used? I've seen it used to avoid the == vs. = typos, but not for other
> > comparisons.
> >
> > Suggest sticking to what is commonly used i.e. ret < 0.
> >
> > > +               goto free_opp;
> > > +
> > > +       cpu_dev = get_cpu_device(GOLD_LEAD);
> >
> > Error check cpu_dev here?
> >
> > > +       ret = PTR_ERR_OR_ZERO(opp_temp =
> > > +
> dev_pm_opp_set_supported_hw(cpu_dev,&versions,1));
> > > +       if (0 > ret)
> > > +               goto free_opp;
> 
> The goto here is wrong

If we are here, then the first dev_pm_opp_set_supported_hw() succeeded. And
should be deallocated before exit with error.

> 
> > > +
> > > +
> > > +       ret =
> PTR_ERR_OR_ZERO(platform_device_register_simple("cpufreq-dt",
> > > +                                                             -1,
> > > + NULL, 0));
> > > +
> > > +       if (0 == ret)
> > > +               return 0;
> > > +
> > > +free_opp:
> > > +       dev_pm_opp_put_supported_hw(opp_temp);
> >
> > This is not needed because dev_pm_opp_set_supported_hw will free
> > memory in case of failure. This call in only needed in case of a
> > successful get.
> 
> But this is still required for the case where platform device registration
fails.
> 
> --
> viresh