Re: [PATCH V3 0/2] ARM: OMAP3+: support cpufreq-cpu0 for device tree boot

[Kevin Hilman <khilman@linaro.org>]

Nishanth Menon <nm@ti.com> writes:

> The following version 3 of the series arose from trying to use BeagleBoard-XM
> (OMAP3 variant) for doing CPU DVFS using cpufreq-cpu0. This series enables the
> generic cpufreq-cpu0 driver to be used in device tree enabled boot while
> maintaining support of the legacy omap-cpufreq driver when used in non device
> tree enabled boot.
>
> However, in order to enable complete SoC entitlement for OMAP platforms, with
> this series, key features are still pending on device tree adaptation for OMAP:
> A) clock framework data transition to DT - this should happen soon, so this
> series hacks the clock node for the time being as suggested in review of
> original series[1].
> B) On processors that use voltage controller, voltage processor (VC/VP hardware
> loop using I2C_SR path) - we have started work on transitioning them to
> regulator framework driven by DT.
> C) Adaptive Body Bias and SmartReflex AVS conversion to DT. [2]
>
> Note: At this point in time, we do not have DT entries for clock on OMAP
> platforms. Common Clock Framework(CCF) could also control regulators[3].
> Once these conversions are complete, there might be minimal cleanup work to
> switch to the new data structure changes.
>
> Key benefit of the series is to allow all relevant TI platforms now to use a
> single cpufreq driver and equivalent frameworks in addition be part of the
> transition to device tree.
> NOTE: As a result of this series:
> 1. omap-cpufreq will be used only in non device tree boot scenario. we should
>    delete this driver once the 100% DT conversion is complete.
> 2. Generic cpufreq-cpu0 will be used only in device tree boot scenario.
>    boot systems.

Yes, I like this direction better.  Thanks for reworking and thanks for
the thorough changelog.

> Key changes in version 3:
> 	- series now rebased on Device tree patches queued for OMAP 3.10
> 	- DT patches introducing OPPs are now merged, so pending patches alone
> 	  are part of the new series.
> 	- omap-cpufreq is now converted to platform_device to address:
> 		http://marc.info/?t=136434901900001&r=1&w=2
>
> version 2 of the series:
> 	http://marc.info/?t=136371570200003&r=1&w=2
> 	available at:
> 	https://github.com/nmenon/linux-2.6-playground/commits/push/cpufreq-cpu0-omap-all-v2
>
> version 1 of the series:
> 	http://marc.info/?t=136329485400005&r=1&w=2
> 	available at:
> 	https://github.com/nmenon/linux-2.6-playground/commits/push/cpufreq-cpu0-omap-all-v1
>
> [1] Original discussion thread which triggered this series:
> 	http://marc.info/?l=linux-pm&m=136304313700602&w=2
> 	https://patchwork.kernel.org/patch/2251841/
> 	https://patchwork.kernel.org/patch/2251851/
> [2] ABB RFC: http://marc.info/?l=linux-omap&m=136449099409794&w=2 
> [3] CCF DVFS patches:
> https://patchwork.kernel.org/patch/2195431/
> https://patchwork.kernel.org/patch/2195421/
> https://patchwork.kernel.org/patch/2195451/
> https://patchwork.kernel.org/patch/2195441/
> https://patchwork.kernel.org/patch/2195461/
>
> Version 3 is now based on for-3.10/dts branch from Benoit:
> 	http://git.kernel.org/cgit/linux/kernel/git/bcousson/linux-omap-dt.git/log/?h=for_3.10/dts
> 	d114294 ARM: dts: AM33XX: Corrects typo in interrupt field in SPI node
>
> Version 3 is also available at:
> 	https://github.com/nmenon/linux-2.6-playground/commits/push/cpufreq-cpu0-omap-all-v3
> 	git link: git://github.com/nmenon/linux-2.6-playground.git
> 	branch: cpufreq-cpu0-omap-all-v3
>
> Test coverage:
> 	test script: http://pastebin.com/zrr8ptge
> Platforms verified:
> 	beaglebone(rev A6a) - AM33xx compatible - http://pastebin.com/GVP2wDVr
> 	beagleboard (rev C1D) - OMAP3430 compatible
> 		- DT enabled boot: http://pastebin.com/2AY1F5Qa
> 		- No DT enabled boot: http://pastebin.com/hDk0gbpU
> 	omap3-beagle-xm -OMAP3630 compatible - http://pastebin.com/5tHAQcLZ
> 	Pandaboard -(OMAP4430 ES2.2) - http://pastebin.com/6D9aDPXT
> 	Pandaboard-ES -(OMAP4460 ES1.1) - http://pastebin.com/ExrBEczr

And thanks also for the broad testing.

One nit about the test report/coverage is I don't see any
test/verification that the voltage is still being scaled based on the DT
based OPPs.  It's easy to verify at least from the regulator PoV that
the voltage is scaled also.

My dumb DVFS test script (below) should work on any busybox rootfs 

Care to give that (or something like it) a try as well?  

With that extra confirmation of testing, I will queue up this series.

Thanks,

Kevin

[1]
#!/bin/sh

REG=`find /sys/class/regulator -follow -maxdepth 2 -name name -exec grep -l mpu {} \;`
mpu_reg=`echo $REG | cut -d'/' -f5`
echo MPU regulator: $mpu_reg

if [ ! -d /sys/devices/system/cpu/cpu0/cpufreq ]; then
  echo "CPUfreq not enabled in kernel."
  exit 0
fi

cd /sys/devices/system/cpu/cpu0/cpufreq
echo -n "Available frequencies: "
cat scaling_available_frequencies
echo -n "Current frequency: "
cat scaling_cur_freq
echo userspace > scaling_governor

for freq in `cat scaling_available_frequencies`; do
  echo ${freq} > scaling_setspeed
  echo -n "current freq: "
  cat scaling_cur_freq
  echo -n "current voltage: "
  cat /sys/class/regulator/${mpu_reg}/microvolts
  sleep 2
done