linux-kernel - Re: [RFC 0/5] drivers: Add boot constraints core

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 30 Jun 2017 09:25:33 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     "Enrico Weigelt, metux IT consult" <enrico.weigelt@...3.net>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>, rnayak@...eaurora.org,
        Shiraz Hashim <shashim@...eaurora.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC 0/5] drivers: Add boot constraints core

On 30-06-17, 11:33, Chen-Yu Tsai wrote:
> AFAIK regulator constraints are supposed to satisfy all users of it.

Right.

> >> >Let me try with an example. A regulator is shared between LCD and DMA
> >> >controller.
> >> >
> >> >Operable ranges of the regulator: 1.8 - 3.0 V
> >> >Range required by LCD: 2.0 - 3.0 V
> >> >Range required by DMA: 1.8 - 2.5 V
> 
> So for the example here, the regulator constraint should be 2.5 - 3.0 V,
> or the intersection of all voltage requirements.

Had a look at regulator_check_consumers() and the range selected by it
is the *highest* min_uV and *lowest* max_uV, to find that intersection
point.

For LCD: min_uV = 2.0 V, max_uV = 3.0 V
For DMA: min_uV = 1.8 V, max_uV = 2.5 V

Highest min_uV = 2.0 V
Lowest max_uV = 2.5 V

And so I mentioned the regulator's final range (that satisfies all
consumers) is 2 - 2.5 V.

Why do you say it should be 2.5 - 3.0 V ?

-- 
viresh