linux-kernel - Re: [RFC] cpufreq: send notifications for intermediate (stable) frequencies

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <CAKohpo=6PQHwT9pP+M0khCne3sxtsKsUnijmTCLKOmgzv0wQkw@mail.gmail.com>
Date:	Fri, 16 May 2014 11:31:50 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Doug Anderson <dianders@...omium.org>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arvind Chauhan <arvind.chauhan@....com>,
	Stephen Warren <swarren@...dia.com>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Russell King <linux@....linux.org.uk>,
	Thomas Abraham <thomas.abraham@...aro.org>
Subject: Re: [RFC] cpufreq: send notifications for intermediate (stable) frequencies

On 15 May 2014 23:43, Doug Anderson <dianders@...omium.org> wrote:
> This will have the side effect of sending twice as many notifications.
>  ...however it does allow for people registering for CPUFREQ
> notifications to be more generic...

That's not a side effect of this approach but the way platforms are
handling it, and there is no way out we can skip that. In case we
do, we will give space for the race to happen and udelay will work
badly..

> Thinking about it, I think you're right that this is the way to go.

Correct :)

> It probably makes sense to wait until Thomas Abraham's patch lands,
> since he's redoing exynos cpufreq to use cpufreq-cpu0.  ...and maybe
> Thomas would be willing to write this patch?

But cpufreq-cpu0 isn't handling this intermediate freq concept, how will
you work around that? Anyway we can get this working for tegra if
stephen agrees.

> What do you think about calling this get_safe_freq().  It took me a
> little while before I realized that this function didn't perform the
> transition to the safe frequency--it just returned it.
>
> ...the comment adds extra confusion since it makes it sound like the
> switch happens right here.

Agree.

>> +                       /* Send POST notification for the target frequency */
>> +                       freqs.new = freq_table[index].frequency;
>
> Don't you need to set freqs.old to the safe_freq?

Agree..
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/