linux-kernel - Re: [RFC 5/5] clk: Add floor and ceiling constraints to clock rates

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Message-ID: <20140627231026.GA26184@ulmo>
Date:	Sat, 28 Jun 2014 01:10:27 +0200
From:	Thierry Reding <thierry.reding@...il.com>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	Mike Turquette <mturquette@...aro.org>,
	Rabin Vincent <rabin.vincent@...ricsson.com>,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 5/5] clk: Add floor and ceiling constraints to clock rates

On Fri, Jun 27, 2014 at 04:57:42PM -0600, Stephen Warren wrote:
> On 06/27/2014 01:57 AM, Tomeu Vizoso wrote:
> > Adds a way for clock consumers to set maximum and minimum rates. This can be
> > used for thermal drivers to set ceiling rates, or by misc. drivers to set
> > floor rates to assure a minimum performance level.
> 
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> 
> > +static struct rate_constraint *__ensure_constraint(struct clk *clk_user,
> > +						   enum constraint_type type)
> 
> > +	if (!found) {
> > +		constraint = kzalloc(sizeof(*constraint), GFP_KERNEL);
> > +		if (!constraint) {
> > +			pr_err("%s: could not allocate constraint\n", __func__);
> 
> Doesn't kzalloc print an error itself if the allocation fails? I've
> certainly seen quite a few patches ripping out custom "allocation
> failed" errors in code.

Yes, these are unnecessary. There's even a checkpatch warning for this
construct nowadays:

	f9a5a624f414 checkpatch: attempt to find unnecessary 'out of memory' messages

Thierry

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