Re: [PATCH v3 1/5] PM / clock_ops: Add pm_clk_add_clk()

[Grygorii Strashko]

On 10/23/2014 06:49 PM, Dmitry Torokhov wrote:
> On Thu, Oct 23, 2014 at 05:22:58PM +0300, Grygorii Strashko wrote:
> > From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> >
> > The existing pm_clk_add() allows to pass a clock by con_id. However,
> > when referring to a specific clock from DT, no con_id is available.
> >
> > Add pm_clk_add_clk(), which allows to specify the struct clk * directly.
> >
> > CC: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> > CC: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> > Reviewed-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> > Reviewed-by: Kevin Hilman <khilman@xxxxxxxxxx>
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> > ---
> >   drivers/base/power/clock_ops.c | 41 +++++++++++++++++++++++++++++++----------
> >   include/linux/pm_clock.h       |  8 ++++++++
> >   2 files changed, 39 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
> > index 7836930..f14b767 100644
> > --- a/drivers/base/power/clock_ops.c
> > +++ b/drivers/base/power/clock_ops.c
> > @@ -53,7 +53,8 @@ static inline int __pm_clk_enable(struct device *dev, struct clk *clk)
> >    */
> >   static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
> >   {
> > -	ce->clk = clk_get(dev, ce->con_id);
> > +	if (!ce->clk)
> > +		ce->clk = clk_get(dev, ce->con_id);
> >   	if (IS_ERR(ce->clk)) {
> >   		ce->status = PCE_STATUS_ERROR;
> >   	} else {
> > @@ -63,15 +64,8 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
> >   	}
> >   }
> >
> > -/**
> > - * pm_clk_add - Start using a device clock for power management.
> > - * @dev: Device whose clock is going to be used for power management.
> > - * @con_id: Connection ID of the clock.
> > - *
> > - * Add the clock represented by @con_id to the list of clocks used for
> > - * the power management of @dev.
> > - */
> > -int pm_clk_add(struct device *dev, const char *con_id)
> > +static int __pm_clk_add(struct device *dev, const char *con_id,
> > +			struct clk *clk)
> >   {
> >   	struct pm_subsys_data *psd = dev_to_psd(dev);
> >   	struct pm_clock_entry *ce;
> > @@ -93,6 +87,8 @@ int pm_clk_add(struct device *dev, const char *con_id)
> >   			kfree(ce);
> >   			return -ENOMEM;
> >   		}
> > +	} else {
>
> You need __clk_get(clk) here, otherwise when you will be removing clocks
> you'll be dropping a reference that does not belong to you (as yiou have
> not taken it).

No, I don't ;)

pm_clk_add_clk is intended to be used with valid pointer on clk,
which means clk_get() has been called already. In our case:
	clk = of_clk_get(dev->of_node, i));
	ret = pm_clk_add_clk(dev, clk);

It's just a different way to fill list of clocks for device,
once pm_clk_add_clk() is called - PM clock framework will be the owner
of clock.

> > +		ce->clk = clk;
> >   	}

regards,
-grygorii

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