linux-kernel - Re: [PATCH] PM / OPP: discard duplicate OPP additions

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Message-ID: <CAKohpom1t2sOWr_S5Xzhx_OG=2qmgkZ5Z6UJ4TKAmJgeq0TU2Q@mail.gmail.com>
Date:	Thu, 15 May 2014 14:25:52 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Chander Kashyap <chander.kashyap@...aro.org>
Cc:	Nishanth Menon <nm@...com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Chander Kashyap <k.chander@...sung.com>,
	Inderpal Singh <inderpal.s@...sung.com>
Subject: Re: [PATCH] PM / OPP: discard duplicate OPP additions

On 15 May 2014 14:16, Chander Kashyap <chander.kashyap@...aro.org> wrote:
> Yes exactly. All users of this API need to be modified to handle
> EEXIST as success.

There are very few:

arch/arm/mach-omap2/opp.c
arch/arm/mach-vexpress/spc.c
drivers/devfreq/exynos/exynos4_bus.c
drivers/devfreq/exynos/exynos5_bus.c

So shouldn't be a problem fixing them..

> To avoid this returning 0 was suggested

But the bigger problem is that all new users have to know about this
and must take care of it, would also result in code duplication.

So, if I think this way:

The purpose of dev_pm_opp_add() is to make sure the OPP is
present with the device, when this function returns..

And with a duplicate entry, we can still confirm that. Over that, I couldn't
think of any situation where the caller wants to react to -EXIST separately.
They will still consider it as success.

So, maybe returning '0' isn't that bad of an idea :)

@Nishanth ?
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