linux-kernel - Re: [PATCH v2 1/5] power: domain: add pm_genpd

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Message-ID: <7h8u54lqbv.fsf@deeprootsystems.com>
Date:	Tue, 08 Dec 2015 10:59:00 -0800
From:	Kevin Hilman <khilman@...nel.org>
To:	Jon Hunter <jonathanh@...dia.com>
Cc:	Eric Anholt <eric@...olt.net>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <mark.rutland@....com>,
	<devicetree@...r.kernel.org>,
	"Ulf Hansson" <ulf.hansson@...aro.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Alexander Aring <alex.aring@...il.com>,
	Pawel Moll <pawel.moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-pm@...r.kernel.org>, Lee Jones <lee@...nel.org>,
	<linux-kernel@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
	<linux-rpi-kernel@...ts.infradead.org>,
	Pavel Machek <pavel@....cz>, "Len Brown" <len.brown@...el.com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/5] power: domain: add pm_genpd_exit

Jon Hunter <jonathanh@...dia.com> writes:

> On 04/12/15 17:45, Eric Anholt wrote:
>> From: Alexander Aring <alex.aring@...il.com>
>> 
>> This patch adds function pm_genpd_exit for undo a pm_genpd_init. This
>> is useful for multiple power domains while probing. If the probing fails
>> after one pm_genpd_init was called we need to undo all previous
>> registrations of generic pm domains inside the gpd_list list.
>> 
>> There is a check on IS_ERR_OR_NULL(genpd) which is useful to check again
>> registered power domains and not registered domains, the driver can use
>> this mechanism to have an array with registered and non-registered power
>> domains, where non-registered power domains are NULL.
>> 
>> Cc: Rafael J. Wysocki <rjw@...ysocki.net>
>> Cc: Kevin Hilman <khilman@...nel.org>
>> Cc: Ulf Hansson <ulf.hansson@...aro.org>
>> Cc: Pavel Machek <pavel@....cz>
>> Cc: Len Brown <len.brown@...el.com>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Signed-off-by: Alexander Aring <alex.aring@...il.com>
>> Signed-off-by: Eric Anholt <eric@...olt.net>
>> Acked-by: Ulf Hansson <ulf.hansson@...aro.org>
>> ---
>>  drivers/base/power/domain.c | 22 ++++++++++++++++++++++
>>  include/linux/pm_domain.h   |  4 ++++
>>  2 files changed, 26 insertions(+)
>> 
>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>> index 167418e..e7aca27 100644
>> --- a/drivers/base/power/domain.c
>> +++ b/drivers/base/power/domain.c
>> @@ -1509,6 +1509,28 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
>>  }
>>  EXPORT_SYMBOL_GPL(pm_genpd_init);
>>  
>> +/**
>> + * pm_genpd_exit - Uninitialize a generic I/O PM domain object.
>> + * @genpd: PM domain object to uninitialize.
>> + */
>> +void pm_genpd_exit(struct generic_pm_domain *genpd)
>> +{
>> +	if (IS_ERR_OR_NULL(genpd))
>> +		return;
>> +
>> +	/* check if domain is still in registered inside the pm subsystem */
>> +	WARN_ON_ONCE(!list_empty(&genpd->master_links) ||
>> +		     !list_empty(&genpd->slave_links) ||
>> +		     !list_empty(&genpd->dev_list));
>> +
>
> Why not return an error here? Seems bad to remove it, if it could still
> be referenced by other domains.

I had pointed this out as well in an earlier review.

> Also not sure if you need to lock around the above test and removing the
> domain.
>
>> +	mutex_lock(&gpd_list_lock);
>> +	list_del(&genpd->gpd_list_node);
>> +	mutex_unlock(&gpd_list_lock);
>> +
>> +	mutex_destroy(&genpd->lock);
>> +}
>> +EXPORT_SYMBOL_GPL(pm_genpd_exit);
>> +
>
> BTW, I had just submitted a similar patch here [0]. So I would also like
> to see such an API added.

Between the two of you, maybe come up with an agreed upon patch and
re-submit.

Kevin

> Cheers
> Jon
>
> [0] http://marc.info/?l=devicetree&m=144924138932726&w=2
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