linux-kernel - Re: [PATCH] clocksource: sh

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Message-ID: <20110531040444.GA1745@linux-sh.org>
Date:	Tue, 31 May 2011 13:04:44 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	linux-kernel@...r.kernel.org, johnstul@...ibm.com,
	linux-sh@...r.kernel.org
Subject: Re: [PATCH] clocksource: sh_tmu: Runtime PM support

On Mon, May 23, 2011 at 05:30:06PM +0900, Paul Mundt wrote:
> On Mon, Apr 25, 2011 at 10:40:26PM +0900, Magnus Damm wrote:
> > From: Magnus Damm <damm@...nsource.se>
> > 
> > Add Runtime PM support to the TMU driver.
> > 
[snip]
> > 
> > +	/* wake up device and enable clock */
> > +	pm_runtime_get_sync(&p->pdev->dev);
> >  	ret = clk_enable(p->clk);
> >  	if (ret) {
> >  		dev_err(&p->pdev->dev, "cannot enable clock\n");
> > +		pm_runtime_put_sync(&p->pdev->dev);
> >  		return ret;
> >  	}
> >  
> At this point the spinlock hasn't been initialized yet, so any of the
> pm_runtime calls are pretty much unsafe. We could manually test
> pm_runtime_enabled() before any of the get/put_sync() calls, but that gets to
> be a bit ugly.

Note that I will be reverting these patches for -rc2 if no progress is
made here. This is a fundamental ordering issue with regards to locking,
and is completely bogus for every SMP platform we have.
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