linux-kernel - Re: [PATCH v2 8/9] PM / Domains: Add support for multi PM domains per device to genpd

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Date:   Wed, 30 May 2018 17:04:37 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        <linux-pm@...r.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Todor Tomov <todor.tomov@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Kevin Hilman <khilman@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v2 8/9] PM / Domains: Add support for multi PM domains per
 device to genpd


On 29/05/18 11:04, Ulf Hansson wrote:
> To support devices being partitioned across multiple PM domains, let's
> begin with extending genpd to cope with these kind of configurations.
> 
> Therefore, add a new exported function genpd_dev_pm_attach_by_id(), which
> is similar to the existing genpd_dev_pm_attach(), but with the difference
> that it allows its callers to provide an index to the PM domain that it
> wants to attach.
> 
> Note that, genpd_dev_pm_attach_by_id() shall only be called by the driver
> core / PM core, similar to how the existing dev_pm_domain_attach() makes
> use of genpd_dev_pm_attach(). However, this is implemented by following
> changes on top.
> 
> Because, only one PM domain can be attached per device, genpd needs to
> create a virtual device that it can attach/detach instead. More precisely,
> let the new function genpd_dev_pm_attach_by_id() register a virtual struct
> device via calling device_register(). Then let it attach this device to the
> corresponding PM domain, rather than the one that is provided by the
> caller. The actual attaching is done via re-using the existing genpd OF
> functions.
> 
> At successful attachment, genpd_dev_pm_attach_by_id() returns the created
> virtual device, which allows the caller to operate on it to deal with power
> management. Following changes on top, provides more details in this
> regards.
> 
> To deal with detaching of a PM domain for the multiple PM domains case,
> let's also extend the existing genpd_dev_pm_detach() function, to cover the
> cleanup of the created virtual device, via make it call device_unregister()
> on it. In this way, there is no need to introduce a new function to deal
> with detach for the multiple PM domain case, but instead the existing one
> is re-used.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> ---
> 
> Changes in v2:
> 	- Fixed comments from Jon. Clarified function descriptions
> 	and changelog.
> 
> ---
>  drivers/base/power/domain.c | 80 +++++++++++++++++++++++++++++++++++++
>  include/linux/pm_domain.h   |  8 ++++
>  2 files changed, 88 insertions(+)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 2af99bfcbe3c..2b496d79159d 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2171,6 +2171,15 @@ struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
>  }
>  EXPORT_SYMBOL_GPL(of_genpd_remove_last);
>  
> +static void genpd_release_dev(struct device *dev)
> +{
> +	kfree(dev);
> +}
> +
> +static struct bus_type genpd_bus_type = {
> +	.name		= "genpd",
> +};
> +
>  /**
>   * genpd_dev_pm_detach - Detach a device from its PM domain.
>   * @dev: Device to detach.
> @@ -2208,6 +2217,10 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
>  
>  	/* Check if PM domain can be powered off after removing this device. */
>  	genpd_queue_power_off_work(pd);
> +
> +	/* Unregister the device if it was created by genpd. */
> +	if (dev->bus == &genpd_bus_type)
> +		device_unregister(dev);
>  }
>  
>  static void genpd_dev_pm_sync(struct device *dev)
> @@ -2298,6 +2311,67 @@ int genpd_dev_pm_attach(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
>  
> +/**
> + * genpd_dev_pm_attach_by_id() - Attach a device to one of its PM domain.
> + * @dev: Device to attach.

Can you update the description of the above as well?

Thanks
Jon

-- 
nvpublic