On Thu, 2015-07-30 at 15:47 +0800, Chen-Yu Tsai wrote:
> On Sat, Jul 25, 2015 at 11:30 PM, Ian Campbell <[email protected]>
> wrote:
> > On Sat, 2015-07-25 at 22:54 +0800, Chen-Yu Tsai wrote:
> >> On Sat, Jul 25, 2015 at 10:46 PM, Leonardo Canducci
> >> <[email protected]> wrote:
> >> > I got lost somewhere in that long thread but I saw cpufreq on
> >> cubie* works
> >> > for someone [0]. It's just a matter of loading two modules. I
> tried
> >> myself
> >> > on my jessie install (kernel from experimental) and can confirm
> >> that:
> >> >
> >> > leo@cubetto:~$ sudo modprobe axp20x-regulator
> >> > leo@cubetto:~$ sudo modprobe cpufreq-dt
> >> > leo@cubetto:~$ ls /sys/devices/system/cpu/cpu0/cpufreq/
> >> > affected_cpus related_cpus
> >> scaling_governor
> >> > cpuinfo_cur_freq scaling_available_frequencies
> >> scaling_max_freq
> >> > cpuinfo_max_freq scaling_available_governors >
> scaling_min_freq
> >> > cpuinfo_min_freq scaling_cur_freq
> >> scaling_setspeed
> >> > cpuinfo_transition_latency scaling_driver
> statsplatform_device_register_simple
> >> >
> >> > How do I make this change persistent?
> >>
> >> Add both module names to /etc/modules.
> >
> > Is there any way to arrange for these modules to be loaded
> > automatically without the user needing to configure it manually,
> like platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
> > any other h/w driver?
> >
> > I'd expect at least the axp20x-regulator driver to get autoloaded
> when
> > the relevant hardware is present. Not sure about the cpufreq-dt
> one, * In particular, when such drivers are built as modules, they can't be
* "hotplugged".
> > but should it not be loaded if the relevant nodes are present?
>
> cpufreq-dt is not a node in the DT. It is added in platform code.
> See arch/arm/mach-sunxi/sunxi.c.
That is this:
platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
> AFAIK all other users of cpufreq-dt use this method. Not sure how
> you can automatically detect this... Supposedly there
> wouldfeatures/all/cpufreq-dt-allow-driver-to-boot-automatically.patch
be
> an event to udev?
I would expect the register to emit something, perhaps all that is
missing is a suitable MODULE_ALIAS. Looking around there seems to be a
fair few MODULE_ALIAS("platform:foo") which appear to serve this
purpose.
...searches..., aha!:
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/350884.html
which is in v4.2-rc1 as:
http://git.kernel.org/linus/07949bf9c63c9a80027fe8452d5fe8b9ba9b3c23
I'll see about backporting that to the 4.1 kernel in Debian until we
move to 4.2.
Ian.
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