Messages in this thread |  | | Date | Thu, 23 Oct 2014 21:04:19 +0300 | From | Grygorii Strashko <> | Subject | Re: [PATCH v3 1/5] PM / clock_ops: Add pm_clk_add_clk() |
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On 10/23/2014 08:13 PM, Dmitry Torokhov wrote: > On Thu, Oct 23, 2014 at 07:18:49PM +0300, Grygorii Strashko wrote: >> 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@glider.be> >>>> >>>> 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@linaro.org> >>>> CC: Dmitry Torokhov <dmitry.torokhov@gmail.com> >>>> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> >>>> Reviewed-by: Kevin Hilman <khilman@linaro.org> >>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> >>>> Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> >>>> --- >>>> 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. > > No, this is not how the rest of refcounted APIs work in the kernel. You > do not take over other's references and if you need to store pointer to > refcounted object you are responsible for taking your own reference. See > how we work with device structures, OF nodes, etc, etc. > > The proper pattern here should be (unless the driver wants to hold on to > the clock for its own purposes): > > clk = of_clk_get(dev->of_node, i)); > ret = pm_clk_add_clk(dev, clk); > clk_put(clk); > > with pm_clk_add_clk() taking and managing _its own_ reference and the > caller (driver) managing _its_ reference. > > So FWIW strong NAK here from me.
Ok. I'll update and resend.
regards, -grygorii
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