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From: Viresh Kumar <viresh.kumar@linaro.org>
To: Leonard Crestez <leonard.crestez@nxp.com>
Cc: "Saravana Kannan" <saravanak@google.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Artur Świgoń" <a.swigon@partner.samsung.com>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Georgi Djakov" <georgi.djakov@linaro.org>,
	"Chanwoo Choi" <cw00.choi@samsung.com>,
	"MyungJoo Ham" <myungjoo.ham@samsung.com>,
	"Kyungmin Park" <kyungmin.park@samsung.com>,
	"Alexandre Bailon" <abailon@baylibre.com>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Subject: Re: [RFC 0/4] opp: Parse required-opp as dev_pm_qos_request
Date: Tue, 20 Aug 2019 14:52:06 +0530	[thread overview]
Message-ID: <20190820092206.7cv3hfvitil2oyg3@vireshk-i7> (raw)
In-Reply-To: <VI1PR04MB70237DE1719FB78C0427A436EEAB0@VI1PR04MB7023.eurprd04.prod.outlook.com>

On 20-08-19, 09:02, Leonard Crestez wrote:
> On 20.08.2019 09:52, Viresh Kumar wrote:
> > On 06-08-19, 14:12, Leonard Crestez wrote:
> >> The "required-opps" property can be placed on any device and point to
> >> any OPP table according to bindings doc but this is not fully
> >> implemented. In practice it can only point from the opp table of a
> >> device to the opp table of a power domain.
> >>
> >> As part of my investingating QOS mechanisms I implemented support for
> >> parsing "required-opps" into a DEV_PM_QOS_MIN_FREQUENCY
> >> dev_pm_qos_request. Since OPPs can be shared between devices this only
> >> works when OPP tables are unshared.
> >>
> >> This would need to be called from a device probe function and any
> >> suspend/resume handling (which likely means disabling the QOS requests)
> >> would also be handled manually by each driver.
> >>
> >> This is RFC mostly because I plan to use the "interconnect" framework
> >> for device requests instead. In theory this could be used if you don't
> >> care about implementing smart aggregation and just want to "set bus freq
> >> to high".
> >>
> >> Devfreq support for dev_pm_qos is here: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fpatch%2F11078475%2F&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7C09dabcdb17434862317508d7253aeac8%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637018807295295723&amp;sdata=vXvTIowhuqDkTxVZMHq%2BQxrKuqYv7n%2FU01ZDA7fdB0c%3D&amp;reserved=0
> > 
> > Some work is going on in related field. Please have a look at this as well.
> 
> I noticed that series but other than touching "required-opp" there is 
> little in common. It seems to be mostly an expansion of the passive 
> governor.
> 
> My series doesn't even depend on devfreq; in theory you could even use 
> required-opp = <&opp_1200mhz> on a cpu device.

What is the exact use case you are targeting here or the problem you are trying
to solve ?

-- 
viresh

  reply	other threads:[~2019-08-20  9:22 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-06 11:12 [RFC 0/4] opp: Parse required-opp as dev_pm_qos_request Leonard Crestez
2019-08-06 11:12 ` [RFC 1/4] opp: Drop const from opp_device struct device Leonard Crestez
2019-08-06 11:12 ` [RFC 2/4] opp: Add dev_pm_opp_table_get_device Leonard Crestez
2019-08-06 11:12 ` [RFC 3/4] opp: Add dev_pm_parse_required_opp_as_qos Leonard Crestez
2019-08-06 11:12 ` [RFC 4/4] PM / QoS: Add dev_pm_qos_get_curr_value Leonard Crestez
2019-08-20  6:52 ` [RFC 0/4] opp: Parse required-opp as dev_pm_qos_request Viresh Kumar
2019-08-20  9:02   ` Leonard Crestez
2019-08-20  9:22     ` Viresh Kumar [this message]
2019-08-20 15:48       ` Leonard Crestez
2019-08-21  5:18         ` Viresh Kumar

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