From: Kevin Hilman <khilman@baylibre.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
ulf.hansson@linaro.org, Len Brown <len.brown@intel.com>,
Pavel Machek <pavel@ucw.cz>,
linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
sboyd@codeaurora.org, nm@ti.com, robh+dt@kernel.org,
lina.iyer@linaro.org, rnayak@codeaurora.org
Subject: Re: [PATCH V2 4/6] PM / domain: Register for PM QOS performance notifier
Date: Fri, 17 Feb 2017 15:54:58 -0800 [thread overview]
Message-ID: <m27f4o4bl9.fsf@baylibre.com> (raw)
In-Reply-To: <a973289cb908a391533a4b940af671beb2e8ace4.1486611268.git.viresh.kumar@linaro.org> (Viresh Kumar's message of "Thu, 9 Feb 2017 09:11:50 +0530")
Viresh Kumar <viresh.kumar@linaro.org> writes:
> Some platforms have the capability to configure the performance state of
> their Power Domains. The performance levels are represented by positive
> integer values, a lower value represents lower performance state.
>
> This patch registers the power domain framework for PM QOS performance
> notifier in order to manage performance state of power domains.
It seems to me it doesm't just register, but actually keeps track of the
performance_state by always tracking the max.
> This also allows the power domain drivers to implement a
> ->set_performance_state() callback, which will be called by the power
> domain core from the notifier routine.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> drivers/base/power/domain.c | 98 ++++++++++++++++++++++++++++++++++++++++++++-
> include/linux/pm_domain.h | 5 +++
> 2 files changed, 101 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a73d79670a64..1158a07f92de 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -367,6 +367,88 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
> return NOTIFY_DONE;
> }
>
> +static void update_domain_performance_state(struct generic_pm_domain *genpd,
> + int depth)
> +{
> + struct generic_pm_domain_data *pd_data;
> + struct generic_pm_domain *subdomain;
> + struct pm_domain_data *pdd;
> + unsigned int state = 0;
> + struct gpd_link *link;
> +
> + /* Traverse all devices within the domain */
> + list_for_each_entry(pdd, &genpd->dev_list, list_node) {
> + pd_data = to_gpd_data(pdd);
> +
> + if (pd_data->performance_state > state)
> + state = pd_data->performance_state;
> + }
This seems to only update the state if it's bigger. Maybe I'm missing
something here, but it seems like won't be able to lower the
performance_state after it's been raised?
> + /* Traverse all subdomains within the domain */
> + list_for_each_entry(link, &genpd->master_links, master_node) {
> + subdomain = link->slave;
> +
> + if (subdomain->performance_state > state)
> + state = subdomain->performance_state;
> + }
So subdomains are always assumed to influence the performance_state of
the parent domains? Is that always the case? I suspect this should be
probably be a reasonable default assumption, but maybe controlled with a
flag.
> + if (genpd->performance_state == state)
> + return;
> +
> + genpd->performance_state = state;
> +
> + if (genpd->set_performance_state) {
> + genpd->set_performance_state(genpd, state);
> + return;
> + }
So is zero not a valid performance_state? That doesn't seem quite right
to me, but either way, it should be documented.
> + /* Propagate only if this domain has a single parent */
Why? This limitation should be explained in the cover letter and
changelog. I would also expect some sort of WARN here since this could
otherwise be a rather silent failures.
[...]
Kevin
next prev parent reply other threads:[~2017-02-18 0:03 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-09 3:41 [PATCH V2 0/6] PM / Domains: Implement domain performance states Viresh Kumar
2017-02-09 3:41 ` [PATCH V2 1/6] PM / QOS: Add default case to the switch Viresh Kumar
2017-02-09 14:24 ` Pavel Machek
2017-02-10 6:00 ` Viresh Kumar
2017-02-10 12:15 ` Pavel Machek
2017-02-13 3:11 ` Viresh Kumar
2017-02-10 21:24 ` Pavel Machek
2017-02-09 3:41 ` [PATCH V2 2/6] PM / QOS: Pass request type to dev_pm_qos_{add|remove}_notifier() Viresh Kumar
2017-02-09 3:41 ` [PATCH V2 3/6] PM / QOS: Add 'performance' request Viresh Kumar
2017-02-21 15:37 ` Ulf Hansson
2017-02-09 3:41 ` [PATCH V2 4/6] PM / domain: Register for PM QOS performance notifier Viresh Kumar
2017-02-17 23:54 ` Kevin Hilman [this message]
2017-02-20 5:01 ` Viresh Kumar
2017-02-21 15:28 ` Ulf Hansson
2017-02-22 3:25 ` Viresh Kumar
2017-02-09 3:41 ` [PATCH V2 5/6] PM / domain: Save/restore performance state at runtime suspend/resume Viresh Kumar
2017-02-17 23:58 ` Kevin Hilman
2017-02-20 9:18 ` Viresh Kumar
2017-02-09 3:41 ` [PATCH V2 6/6] PM / OPP: Add support to parse domain-performance-state Viresh Kumar
2017-02-17 5:38 ` [PATCH V2 0/6] PM / Domains: Implement domain performance states Viresh Kumar
2017-02-17 7:46 ` Ulf Hansson
2017-02-17 23:22 ` Kevin Hilman
2017-02-20 9:35 ` Viresh Kumar
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