gumstix

Additional info:

My waterstorm shipped with a slightly antique 2.6.34 kernel (circa 2010) on
the NAND. Accepts an 800MHz mpurate parameter and *appears* to operate at
that frequency, but I notice that all the kernel boot messages refer to
'omap' devices, rather than davinci ones.


On Fri, Feb 8, 2013 at 12:06 PM, Akram Hameed <akramh@...> wrote:

> Howdy folks,
>
> Just coming to terms with yocto and simultaneously testing out a
> Waterstorm I just received. One or two questions:
>
> 1) SoC in my WaterStorm is a DaVinci. When I set up my config for yocto I
> get a default machine of 'overo'. When I build things using the stable
> branch, I get a kernel (3.5.0) generated with CONFIG_ARCH_OMAP, rather than
> CONFIG_ARCH_DAVINCI, and all the associated OMAP stuff. Surely there should
> be an option for the DAVINCI stuff? I mean, I can manually edit my
> defconfig, but maybe I am missing the point here. I know things will work
> pretty much using an OMAP config, but they're not identical things...
>
> Is there a different machine specifier for the storm series?
>
> 2) What is the recommended way to change cpu frequency in these newer
> kernels? I have, historically, used an mpurate arg to the kernel. Is this
> still OK, or should I be invoking a governor?
>
> Cheers,
>
> Akram
>

On 2/7/2013 8:06 PM, Akram Hameed wrote:
> Just coming to terms with yocto and simultaneously testing out a Waterstorm I
> just received. One or two questions:
>
> 1) SoC in my WaterStorm is a DaVinci. When I set up my config for yocto I get
> a default machine of 'overo'. When I build things using the stable branch, I
> get a kernel (3.5.0) generated with CONFIG_ARCH_OMAP, rather than
> CONFIG_ARCH_DAVINCI, and all the associated OMAP stuff. Surely there should be
> an option for the DAVINCI stuff? I mean, I can manually edit my defconfig, but
> maybe I am missing the point here. I know things will work pretty much using
> an OMAP config, but they're not identical things...

I can't comment on the yocto and official overo build details, but 
CONFIG_ARCH_DAVINCI is for an older DaVinci architecture.  The DM3730 
architecture is very close to the OMAP3530.  A few runtime checks handle the 
differences.

> 2) What is the recommended way to change cpu frequency in these newer kernels?
> I have, historically, used an mpurate arg to the kernel. Is this still OK, or
> should I be invoking a governor?

I've always used the userspace cpufreq governor and written to the 
scaling_setspeed file in /sys.  mpurate should go through the same mechanism 
if it still works.

-- 
Jeff DeFouw <jeffd@...>
Programmer
Grand Rapids Technologies

Howdy Jeff,

Thanks for the info; have built and plugged my 3.5.0 OMAP-based kernel in
to the Waterstorm. Things appear to work nicely, with a few curiosities.

1) the mpurate argument does not appear to be reflected in my BogoMIPS
value; where historically (3.0-pm) I could set mpurate to 720 (on an Overo
Water), and BogoMIPs would reflect the change (from 500 MHz), setting the
mpurate parameter here results in my BogoMIPS sitting at ~600 still, but my
'cpuinfo_cur_freq' suggests things are currently clocked at 800 MHz.

2) Setting a rate of 600 as the mpurate again reflects correctly in.my
cpuinfo_cur_freq, but BogoMIPS shows up as 597 as usual.

3) Setting cpufreq via the userspace governor has the same effect as the
previous two points.

I think I will contrive of a processor-intensive task so as to be sure
things are actually changing somewhat...

Cheers,

Akram

On Sat, Feb 9, 2013 at 9:32 AM, Jeff DeFouw <jeffd@...> wrote:

> On 2/7/2013 8:06 PM, Akram Hameed wrote:
> > Just coming to terms with yocto and simultaneously testing out a
> Waterstorm I
> > just received. One or two questions:
> >
> > 1) SoC in my WaterStorm is a DaVinci. When I set up my config for yocto
> I get
> > a default machine of 'overo'. When I build things using the stable
> branch, I
> > get a kernel (3.5.0) generated with CONFIG_ARCH_OMAP, rather than
> > CONFIG_ARCH_DAVINCI, and all the associated OMAP stuff. Surely there
> should be
> > an option for the DAVINCI stuff? I mean, I can manually edit my
> defconfig, but
> > maybe I am missing the point here. I know things will work pretty much
> using
> > an OMAP config, but they're not identical things...
>
> I can't comment on the yocto and official overo build details, but
> CONFIG_ARCH_DAVINCI is for an older DaVinci architecture.  The DM3730
> architecture is very close to the OMAP3530.  A few runtime checks handle
> the
> differences.
>
> > 2) What is the recommended way to change cpu frequency in these newer
> kernels?
> > I have, historically, used an mpurate arg to the kernel. Is this still
> OK, or
> > should I be invoking a governor?
>
> I've always used the userspace cpufreq governor and written to the
> scaling_setspeed file in /sys.  mpurate should go through the same
> mechanism
> if it still works.
>
> --
> Jeff DeFouw <jeffd@...>
> Programmer
> Grand Rapids Technologies
>
>
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