linux-kernel - Re: [PATCH 2/4] i2c: designware-platdrv: fix unbalanced clk enable and prepare

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Message-ID: <20160421161922.0068ef51@xhacker>
Date:	Thu, 21 Apr 2016 16:19:22 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
CC:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	<mika.westerberg@...ux.intel.com>, <wsa@...-dreams.de>,
	<linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/4] i2c: designware-platdrv: fix unbalanced clk enable
 and prepare

Dear Jarkko,

On Thu, 21 Apr 2016 10:39:50 +0300 Jarkko Nikula wrote:

> On 04/21/2016 05:40 AM, Jisheng Zhang wrote:
> > Dear Jarkko, Andy,
> >
> > On Wed, 20 Apr 2016 17:16:00 +0300 Andy Shevchenko wrote:
> >  
> >> On Wed, 2016-04-20 at 15:55 +0300, Jarkko Nikula wrote:  
> >>> I see Andy's 1cb715ca4694 ("i2c-designware: move to managed functions
> >>> (devm_*)") removed it but at quick look drivers/clk/clk-devres.c:
> >>> devm_clk_release() calls only clk_put and I don't see disable is done
> >>> down the path.  
> >>
> >> The following is a mistake of the mentioned patch.
> >> -       clk_disable_unprepare(dev->clk);
> >>
> >> I did at the same mistake in dw_dmac driver which had been fixed later
> >> in the commit 8be4f523b480 ("dmaengine: dw: fix regression in dw_probe()
> >> function").
> >>  
> >
> > As Andy pointed out, managed devm_clk_get can only automatically put clk
> > but doesn't unprepare and disable the clk
> >  
> Ok, then it makes sense to move this fix first in the series and queue 
> for stable v4.5+. Then another from you, Andy or me for kernels before 
> b33af11de236 ("i2c: designware: Do not require clock when SSCN and FFCN 
> are provided") that introduced the i2c_dw_plat_prepare_clk().

Sounds a good idea. Will send a separate fix for this purpose soon.

Thanks,
Jisheng