Message-ID: <b16a25d0-3f39-3231-bc80-d79739dc0168@quicinc.com>
Date: Fri, 9 Aug 2024 14:57:11 +0530
From: Dikshita Agarwal <quic_dikshita@...cinc.com>
To: Dhruva Gole <d-gole@...com>
CC: "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>,
        "Len
 Brown" <len.brown@...el.com>,
        Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>,
        Stanimir Varbanov
	<stanimir.k.varbanov@...il.com>,
        Vikash Garodia <quic_vgarodia@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>,
        "Konrad Dybcio"
	<konrad.dybcio@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Ulf
 Hansson <ulf.hansson@...aro.org>,
        Bryan O'Donoghue
	<bryan.odonoghue@...aro.org>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-media@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] PM: domains: add device managed version of
 dev_pm_domain_attach|detach_list()



On 8/9/2024 9:49 AM, Dhruva Gole wrote:
> Hi,
> 
> On Aug 08, 2024 at 16:29:12 +0530, Dikshita Agarwal wrote:
>>
>>
>> On 8/8/2024 4:25 PM, Dikshita Agarwal wrote:
>>>
>>>
>>> On 8/8/2024 4:11 PM, Dhruva Gole wrote:
>>>> On Aug 07, 2024 at 12:45:46 +0530, Dikshita Agarwal wrote:
>>>>> Add the devres-enabled version of dev_pm_domain_attach|detach_list.
>>>>> If client drivers use devm_pm_domain_attach_list() to attach the
>>>>> PM domains, devm_pm_domain_detach_list() will be invoked implicitly
>>>>> during remove phase.
>>>>>
>>>>> Signed-off-by: Dikshita Agarwal <quic_dikshita@...cinc.com>
>>>>> ---
>>>>>  drivers/base/power/common.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>>>>  include/linux/pm_domain.h   | 13 +++++++++++++
>>>>>  2 files changed, 57 insertions(+)
>>>>>
>>>>> diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
>>>>> index 327d168..729d6c2 100644
>>>>> --- a/drivers/base/power/common.c
>>>>> +++ b/drivers/base/power/common.c
>>>>> @@ -277,6 +277,50 @@ int dev_pm_domain_attach_list(struct device *dev,
>>>>>  EXPORT_SYMBOL_GPL(dev_pm_domain_attach_list);
>>>>>  
>>>>>  /**
>>>>> + * devm_pm_domain_detach_list - devres-enabled version of dev_pm_domain_detach_list.
>>>>> + * @_list: The list of PM domains to detach.
>>>>> + *
>>>>> + * This function reverse the actions from devm_pm_domain_attach_list().
>>>>> + * it will be invoked during the remove phase from drivers implicitly if driver
>>>>> + * uses devm_pm_domain_attach_list() to attach the PM domains.
>>>>> + */
>>>>> +void devm_pm_domain_detach_list(void *_list)
> 
> My problem is with the type of parameter used being void, why void?
> Why not be explicit about it and call it dev_pm_domain_list *list like
> the non-devres version of the API?
> 
devm_add_action_or_reset API expects the argument as void (*)(void *).

Below are code references following the same way:
https://elixir.bootlin.com/linux/v6.11-rc2/source/drivers/devfreq/devfreq.c#L1332
https://elixir.bootlin.com/linux/v6.11-rc2/source/drivers/clk/clk.c#L1033

If I change the type of argument as you are suggesting, it will throw
compilation error.
"expected 'void (*)(void *)' but argument is of type 'void (*)(struct
dev_pm_domain_list *)'"
>>>>> +{
>>>>> +	struct dev_pm_domain_list *list = _list;
>>>>> +
>>>>> +	dev_pm_domain_detach_list(list);
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(devm_pm_domain_detach_list);
>>>>> +
>>>>> +/**
>>>>> + * devm_pm_domain_attach_list - devres-enabled version of dev_pm_domain_attach_list
>>>>> + * @dev: The device used to lookup the PM domains for.
>>>>> + * @data: The data used for attaching to the PM domains.
>>>>> + * @list: An out-parameter with an allocated list of attached PM domains.
>>>>> + *
>>>>> + * NOTE: this will also handle calling devm_pm_domain_detach_list() for
>>>>> + * you during remove phase.
>>>>> + *
>>>>> + * Returns the number of attached PM domains or a negative error code in case of
>>>>> + * a failure.
>>>>> + */
>>>>> +int devm_pm_domain_attach_list(struct device *dev,
>>>>> +			       const struct dev_pm_domain_attach_data *data,
>>>>> +			       struct dev_pm_domain_list **list)
>>>>> +{
>>>>> +	int ret, num_pds = 0;
>>>>
>>>> Do we require this =0? In the very next line you're initing this anyway.
>>>>
>>> That's correct, will fix this. Thanks.
>>>>> +
>>>>> +	num_pds = dev_pm_domain_attach_list(dev, data, list);
>>>>> +
>>>>> +	ret = devm_add_action_or_reset(dev, devm_pm_domain_detach_list, *list);
>>>>> +	if (ret)
>>>>> +		return ret;
>>>>> +
>>>>> +	return num_pds;
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(devm_pm_domain_attach_list);
>>>>> +
>>>>> +/**
>>>>>   * dev_pm_domain_detach - Detach a device from its PM domain.
>>>>>   * @dev: Device to detach.
>>>>>   * @power_off: Used to indicate whether we should power off the device.
>>>>> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
>>>>> index 772d328..efd517017 100644
>>>>> --- a/include/linux/pm_domain.h
>>>>> +++ b/include/linux/pm_domain.h
>>>>> @@ -450,8 +450,12 @@ struct device *dev_pm_domain_attach_by_name(struct device *dev,
>>>>>  int dev_pm_domain_attach_list(struct device *dev,
>>>>>  			      const struct dev_pm_domain_attach_data *data,
>>>>>  			      struct dev_pm_domain_list **list);
>>>>> +int devm_pm_domain_attach_list(struct device *dev,
>>>>> +			       const struct dev_pm_domain_attach_data *data,
>>>>> +			       struct dev_pm_domain_list **list);
>>>>>  void dev_pm_domain_detach(struct device *dev, bool power_off);
>>>>>  void dev_pm_domain_detach_list(struct dev_pm_domain_list *list);
>>>>> +void devm_pm_domain_detach_list(void *list);
>>>>
>>>> Why not just call it dev_pm_domain_list *list? Why make it void? I am a
>>>> bit confused.
>>>>
>>> This comment is not clear to me, could you pls elaborate?
>> Ah! Sorry, pls ignore my below comment. But can you still explain the
>> concern here?
> 
> I have explained above near the func definition.
> 

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