linux-kernel - Re: [PATCH 14/17] i2c: nomadik: Fixup deployment of runtime PM

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Date:	Mon, 10 Feb 2014 11:14:46 +0100
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Russell King <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Alessandro Rubini <rubini@...pv.it>,
	Wolfram Sang <wsa@...-dreams.de>,
	Chris Ball <chris@...ntf.net>, Mark Brown <broonie@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	linux-spi@...r.kernel.org,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 14/17] i2c: nomadik: Fixup deployment of runtime PM

On 5 February 2014 15:34, Linus Walleij <linus.walleij@...aro.org> wrote:
> On Tue, Feb 4, 2014 at 4:58 PM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
>> Since the device is active while a successful probe has been completed,
>> the reference counting for the clock will be screwed up and never reach
>> zero.
>>
>> The issue is resolved by implementing runtime PM callbacks and let them
>> handle the resources accordingly, including the clock.
>>
>> Cc: Alessandro Rubini <rubini@...pv.it>
>> Cc: Linus Walleij <linus.walleij@...aro.org>
>> Cc: Wolfram Sang <wsa@...-dreams.de>
>> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
>
> Hm do I read it right as patch 13 breaks runtime PM by leaving
> the device active after probe() and this patch
> 14 fixes it again? Maybe these two patches should be squashed
> then.

You are right; but the driver will still be working, you just don't
get the benefit from inactivating the device at request inactivity -
as you pointed out.

The reason for why I wanted to do this as separate steps was to make
it easier for reviewing, otherwise the patch(es) would have been quite
big and messy. I am for sure open to  adopt to your proposal, but just
wanted to give you some more background, before I go ahead and send a
v2.

Kind regards
Ulf Hansson

>
> Yours,
> Linus Walleij
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