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

[Grygorii Strashko <grygorii.strashko@ti.com>]

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.

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

regards,
-grygorii