linux-kernel - Re: [PATCH v2 1/2] PM: domains: add device managed version of dev_pm_domain_attach|detach

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Message-ID: <20240809041913.frh4ooo25gfakwia@lcpd911>
Date: Fri, 9 Aug 2024 09:49:13 +0530
From: Dhruva Gole <d-gole@...com>
To: Dikshita Agarwal <quic_dikshita@...cinc.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()

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?

> >>> +{
> >>> +	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.

-- 
Best regards,
Dhruva Gole <d-gole@...com>