linux-kernel - Re: [PATCH RFC RFT 1/3] clk: per-user clk prepare & enable ref counts

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Date:	Mon, 10 Aug 2015 12:31:27 -0700
From:	Michael Turquette <mturquette@...libre.com>
To:	Maxime Coquelin <maxime.coquelin@...com>,
	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Cc:	sboyd@...eaurora.org, lee.jones@...aro.org,
	maxime.ripard@...e-electrons.com, s.hauer@...gutronix.de,
	geert@...ux-m68k.org
Subject: Re: [PATCH RFC RFT 1/3] clk: per-user clk prepare & enable ref counts

Quoting Maxime Coquelin (2015-08-10 06:47:51)
> Hi Mike,
> 
> On 08/07/2015 09:09 PM, Michael Turquette wrote:
> > This patch adds prepare and enable reference counts for the per-user
> > handles that clock consumers have for a clock node. This patch warns if
> > an imbalance occurs while trying to disable or unprepare a clock and
> > aborts, leaving the hardware unaffected.
> >
> > Signed-off-by: Michael Turquette <mturquette@...libre.com>
> > ---
> >   drivers/clk/clk.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index 898052e..72feee9 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -84,6 +84,8 @@ struct clk {
> >       unsigned long min_rate;
> >       unsigned long max_rate;
> >       struct hlist_node clks_node;
> > +     unsigned int enable_count;
> > +     unsigned int prepare_count;
> >   };
> >   
> >   /***           locking             ***/
> > @@ -600,6 +602,9 @@ void clk_unprepare(struct clk *clk)
> >               return;
> >   
> >       clk_prepare_lock();
> > +     if (WARN_ON(clk->prepare_count == 0))
> Isn't clk_prepare_unlock()call missing here before return?

Doh! Good catch.

Thanks,
Mike

> > +             return;
> > +     clk->prepare_count--;
> >       clk_core_unprepare(clk->core);
> >       clk_prepare_unlock();
> >   }
> > @@ -657,6 +662,7 @@ int clk_prepare(struct clk *clk)
> >               return 0;
> >   
> >       clk_prepare_lock();
> > +     clk->prepare_count++;
> >       ret = clk_core_prepare(clk->core);
> >       clk_prepare_unlock();
> >   
> > @@ -707,6 +713,9 @@ void clk_disable(struct clk *clk)
> >               return;
> >   
> >       flags = clk_enable_lock();
> > +     if (WARN_ON(clk->enable_count == 0))
> Ditto.
> > +             return;
> > +     clk->enable_count--;
> >       clk_core_disable(clk->core);
> >       clk_enable_unlock(flags);
> >   }
> 
> Regards,
> Maxime
> --
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