[oe] hawkboard at 456 Mhz?

[Frans Meulenbroeks]

2010/3/22 Frans Meulenbroeks <fransmeulenbroeks at gmail.com>:
> 2010/3/22 Koen Kooi <k.kooi at student.utwente.nl>:
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>> On 21-03-10 20:38, Frans Meulenbroeks wrote:
>>> 2010/3/21 Koen Kooi <k.kooi at student.utwente.nl>:
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>>>> On 21-03-10 13:57, Frans Meulenbroeks wrote:
>>>>> Hi,
>>>>>
>>>>> In the openembedded repository I saw the following patch:
>>>>> http://cgit.openembedded.org/cgit.cgi/openembedded/tree/recipes/linux/linux-davinci/da850_omapl138_opp456mhz.patch
>>>>> This seems to suggest that it is possible to run the hawkboard at 456
>>>>> Mhz (and yeah: I know it is out of spec and out of warranty, but for
>>>>> an experiment it would be quite helpful for me).
>>>>> I've build the kernel with openembedded, the patch is applied,
>>>>> CONF_CPU_FREQ is defined, but the control hook in /sys is not there.
>>>>> I've also tried tweaking the file with the settings (ds850.c) but to no avail.
>>>>>
>>>>> Anyone a suggestion on how to get this done?
>>>>
>>>> You need a newer kernel that doesn't rely on the TPS part for cpufreq
>>>> (hawkboard lacks a PMIC, the evm uses the TPS). You can build from the
>>>> ti/staging[1] branch to get such a kernel.
>>>>
>>>> Or wait a week for that branch to get merge, internal testing is finally
>>>> wrapping up.
>>>>
>>>> [1] http://gitorious.org/angstrom/openembedded/commits/ti/staging
>>>
>>>
>>> Koen,
>>>
>>> Thanks alot!
>>> As patience is something that I don't have an overdose of, I decided
>>> not to waste any on this issue.
>>> So I checked out the git and rebuild the kernel. Works like a charm.
>>>
>>> For those who want to reproduce this:
>>> Be sure to adapt defconfig (CONFIG_DA8XX_MAX_SPEED_456=y)
>>>
>>> I changed the speed setting with cpuspeed, this one is not on the
>>> angstrom feed, so you need to build it yourself too.
>>
>> I use cpufrequtils, is cpuspeed a better option?
>
> I was unaware of cpufrequtils and bumped into cpuspeed, so I used that.
> I just quickly browsed the manpage of cpufreq-set and it would have
> served me better (as cupfreq-set has a -f option to force the speed
> and cpuspeed is controlled to signals.
> Here is the manpage for cpuspeed: http://linux.die.net/man/8/cpuspeed
>
> Btw I would have expected that I could also directly poke in /sys to
> change the speed but the one attempt I did gave an error. Might be
> that I just used the wrong var
> (actually i probably had to use scaling_set_speed and I probably used
> something like actual_speed or current_speed).
>
> Frans.
>
> PS: i've briefly peeked at the processor doc: would it be possible to
> push things even further (e.g. to 600 Mhz). Of course I know this is
> out of warranty, but that is 456 too :-) I'm still missing some info
> on how to play with what to do an educated attempt (it is manly the
> voltage related settings I feel unsure about).
>
Forgot to mention: google yesterday gave me also a gtk variant:
gtk-cpuspeedy and a kde one: klaptopdaemon
didn't try these.

FM