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

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Date:	Wed, 20 Apr 2016 17:16:00 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
	Jisheng Zhang <jszhang@...vell.com>,
	mika.westerberg@...ux.intel.com, wsa@...-dreams.de
Cc:	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

On Wed, 2016-04-20 at 15:55 +0300, Jarkko Nikula wrote:
> On 04/14/2016 03:53 PM, Jisheng Zhang wrote:
> > 
> > If i2c_dw_probe() fail, we should call i2c_dw_plat_prepare_clk() to
> > disable and unprepare the clk, otherwise the clk enable and prepare
> > is left unbalanced.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> > ---
> >   drivers/i2c/busses/i2c-designware-platdrv.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index 00f9e99..1488cea 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -268,6 +268,8 @@ rpm_disable:
> >   		pm_runtime_put_noidle(&pdev->dev);
> >   	}
> > 
> > +	i2c_dw_plat_prepare_clk(dev, false);
> > +
> >   	return r;
> >   }
> > 
> This is a bit unclear to me does devm_clk_get take care of clk
> disabling 
> in case of probe error or driver removal?
> 
> 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").

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy