linux-kernel - Re: [PATCH] PM / OPP: Add dev_pm_opp_{set|put}

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Message-ID: <20170621050038.GQ3942@vireshk-i7>
Date:   Wed, 21 Jun 2017 10:30:38 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Stephen Boyd <sboyd@...eaurora.org>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PM / OPP: Add dev_pm_opp_{set|put}_clkname()

On 20-06-17, 14:08, Stephen Boyd wrote:
> On 06/20, Viresh Kumar wrote:
> > + */
> > +struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name)
> > +{
> > +	struct opp_table *opp_table;
> > +	int ret;
> > +
> > +	opp_table = dev_pm_opp_get_opp_table(dev);
> > +	if (!opp_table)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	/* This should be called before OPPs are initialized */
> > +	if (WARN_ON(!list_empty(&opp_table->opp_list))) {
> > +		ret = -EBUSY;
> > +		goto err;
> > +	}
> > +
> > +	/* Already have clkname set */
> > +	if (opp_table->clk_name) {
> > +		ret = -EBUSY;
> > +		goto err;
> > +	}
> > +
> > +	opp_table->clk_name = kstrdup(name, GFP_KERNEL);
> > +	if (!opp_table->clk_name) {
> 
> Is there a reason to duplicate clk_name instead of using the clk
> structure returned from clk_get()? Is it because we may already
> have opp_table->clk set from default init? Why can't we always
> clk_put() the clk structure if it's !IS_ERR() and then allow
> dev_pm_opp_set_clkname() to be called many times in succession?
> Long story short, I don't see the benefit to allocating the name
> again here just to use it as a mechanism to know if the APIs have
> been called symmetrically.

Yeah, it was kind of required in what I was trying to do earlier, but
not anymore.

-- 
viresh