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: <CAPDyKFpUMmveKQ2Pi33VwcvG9tsMQHEcAg88icf7v9mzzm+k4Q@mail.gmail.com>
Date: Tue, 13 Aug 2024 12:52:53 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
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>, "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 Wed, 7 Aug 2024 at 09:16, Dikshita Agarwal <quic_dikshita@...cinc.com> 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)
> +{
> +       struct dev_pm_domain_list *list = _list;
> +
> +       dev_pm_domain_detach_list(list);
> +}
> +EXPORT_SYMBOL_GPL(devm_pm_domain_detach_list);

I think this function should be internal and hence made static -
unless there is a good reason to export it?

> +
> +/**
> + * 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;

There is no need to initialize num_pds to 0 here, as the below calls
take care of it.

> +
> +       num_pds = dev_pm_domain_attach_list(dev, data, list);
> +

We should add a check if num_pds is zero here, as in that case there
is no reason to add a devres callback for it.

> +       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);

[...]

Kind regards
Uffe