linux-kernel - Re: [PATCH V7 00/13] drivers: Boot Constraint core

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Message-ID: <1523367652.4981.9.camel@pengutronix.de>
Date:   Tue, 10 Apr 2018 15:40:52 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Georgi Djakov <georgi.djakov@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        robdclark@...il.com, s.hauer@...gutronix.de, shawnguo@...nel.org,
        fabio.estevam@....com, nm@...com, xuwei5@...ilicon.com,
        robh+dt@...nel.org, olof@...om.net
Subject: Re: [PATCH V7 00/13] drivers: Boot Constraint core

Hi Georgi,

Am Freitag, den 30.03.2018, 18:24 +0300 schrieb Georgi Djakov:
[...]
> The interconnect core takes requests from consumer drivers for their
> bandwidth needs and configures the hardware to keep the lowest possible
> power profile. I think that the boot constraint patches would be useful
> to make a board run at maximum performance during boot, until all
> consumer drivers are probed and all bandwidth requests are taken into
> account.

Can you please describe how this bootconstraints core integration is
simpler than a "run things at max performance until late kernel init",
which could be triggered by a simple initcall similar to what is done
for clocks and regulators?

To me the bootcontraints stuff looks like a fairly complex solution and
your use-case doesn't even sound like you strictly want to keep a
bootloader configuration, but rather run things at max performance
until you are reasonably sure that you got all the necessary bandwidth
requests.

Regards,
Lucas