linux-kernel - Re: [PATCH] PM / OPP: of_property_count_u32

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Date:	Sat, 19 Sep 2015 15:22:19 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, nm@...com,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Len Brown <len.brown@...el.com>,
	open list <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] PM / OPP: of_property_count_u32_elems() can return errors

On 09/18, Viresh Kumar wrote:
> On 17-09-15, 11:13, Stephen Boyd wrote:
> > > +	count = of_property_count_u32_elems(opp->np, "opp-microvolt");
> > > +	if (count < 0) {
> > 
> > We can't test count for -EINVAL to detect the missing property
> > because -EINVAL is also returned on a non-multiple of u32 length
> > property? Maybe we shouldn't worry about that case and turn
> > -EINVAL into 0.
> 
> So you are saying that we go ahead without regulators if a incorrect
> values are present in opp-microvolt? i.e. even if the length property
> was invalid, we return 0 from this function.
> 
> The problem here is that we will try changing the frequency without
> changing the regulator in that case, and it might not be safe for the
> platform, isn't it?
> 

Do we care if a platform has changed the length of the property
to something that isn't a multiple of u32? That sounds very rare,
that's all. I agree it's a bug.

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