linux-kernel - Re: [PATCH] cpufreq: cpufreq-cpu0: Use a sane boot frequency when booting with a mismatched bootloader configuration

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Message-ID: <528BA355.4040008@ti.com>
Date:	Tue, 19 Nov 2013 11:43:49 -0600
From:	Nishanth Menon <nm@...com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	Shawn Guo <shawn.guo@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Carlos Hernandez <ceh@...com>
Subject: Re: [PATCH] cpufreq: cpufreq-cpu0: Use a sane boot frequency when
 booting with a mismatched bootloader configuration

On 11/19/2013 11:10 AM, Viresh Kumar wrote:
> On 19 November 2013 21:18, Nishanth Menon <nm@...com> wrote:
>> is that true for userspace governor
>> (CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE)?
>> /sys/devices/system/cpu/cpu0/cpufreq $ cat scaling_available_frequencies
>> 500000 1000000 1500000
>>
>> /sys/devices/system/cpu/cpu0/cpufreq $ cat scaling_cur_freq
>> 1100000
> 
> No, but userspace governor must take care of this stuff as it want's
> to change freq from userspace..
> 

Right, the point is that CPUFREQ_GOV_LIMITS wont help in the case when
it is within min-max bound.. the first transition will help bring it
to a sane value - that I agree.

>> OMAP5-UEVM will remain at this frequency for a long period of time
>> with AVS voltage(Adaptive Voltage Scaling technique used in OMAP to
>> optimize operational voltage) that was meant for 1GHz! that is
>> definitely not stable if there is no further transition to a valid
>> frequency.
> 
> I understand that point, but will this stay for a long time at that freq?
> Why aren't governors coming into picture here?

we depend on the first transition to take us to a sane configuration -
but we cannot predict when and if it will happen.


-- 
Regards,
Nishanth Menon
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