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From: Leonard Crestez <leonard.crestez@nxp.com>
To: Viresh Kumar <viresh.kumar@linaro.org>,
	Saravana Kannan <saravanak@google.com>
Cc: "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 09:02:39 +0000	[thread overview]
Message-ID: <VI1PR04MB70237DE1719FB78C0427A436EEAB0@VI1PR04MB7023.eurprd04.prod.outlook.com> (raw)
In-Reply-To: 20190820065202.fet4ctxk4jku7ul2@vireshk-i7

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.

--
Regards,
Leonard

  reply	other threads:[~2019-08-20  9:02 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 [this message]
2019-08-20  9:22     ` Viresh Kumar
2019-08-20 15:48       ` Leonard Crestez
2019-08-21  5:18         ` Viresh Kumar

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