linux-kernel - Re: [EXT] Re: [PATCH 2/2] cpufreq: dt-platdev: Support building cpufreq platdev driver as module

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Message-ID: <ZO7O056MxAnjvGxu@aurel32.net>
Date:   Wed, 30 Aug 2023 07:08:35 +0200
From:   Aurelien Jarno <aurelien@...el32.net>
To:     Zhipeng Wang <zhipeng.wang_1@....com>
Cc:     "rafael@...nel.org" <rafael@...nel.org>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [EXT] Re: [PATCH 2/2] cpufreq: dt-platdev: Support building
 cpufreq platdev driver as module

Hi,

On 2023-08-30 03:09, Zhipeng Wang wrote:
> Hi Aurelien,
> 
> I'm not sure why we need to make cpufreq-dt-platdev autoloading, does it make sense? As I understand it we need to actively modprobe cpufreq-dt-platdev, why not?

This is needed to recover the old behavior, where if a CPU supports
cpufreq-dt, it get loaded automatically. Now users has to modprobe
cpufreq-dt-platdev explicitly to get cpufreq-dt to work. This seems like
a regression to me.

Of course one can explicitly make CPUFREQ_DT_PLATDEV=y, but the default
is to build cpufreq-dt-platdev as module when cpufreq-dt is built as
module.

Regards
Aurelien

> > -----Original Message-----
> > From: Aurelien Jarno <aurelien@...el32.net>
> > Sent: 2023年8月30日 2:01
> > To: Zhipeng Wang <zhipeng.wang_1@....com>
> > Cc: rafael@...nel.org; viresh.kumar@...aro.org; linux-pm@...r.kernel.org;
> > linux-kernel@...r.kernel.org
> > Subject: [EXT] Re: [PATCH 2/2] cpufreq: dt-platdev: Support building cpufreq
> > platdev driver as module
> > 
> > Caution: This is an external email. Please take care when clicking links or opening
> > attachments. When in doubt, report the message using the 'Report this email'
> > button
> > 
> > 
> > Hi,
> > 
> > On 2023-05-24 15:34, Zhipeng Wang wrote:
> > > Make the cpufreq platdev driver as tristate so that it can be built as
> > > loadable module.
> > >
> > > Signed-off-by: Zhipeng Wang <zhipeng.wang_1@....com>
> > > ---
> > >  drivers/cpufreq/Kconfig | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig index
> > > 2c839bd2b051..dda3a78bfd5c 100644
> > > --- a/drivers/cpufreq/Kconfig
> > > +++ b/drivers/cpufreq/Kconfig
> > > @@ -218,7 +218,7 @@ config CPUFREQ_DT
> > >         If in doubt, say N.
> > >
> > >  config CPUFREQ_DT_PLATDEV
> > > -     bool
> > > +     tristate "Generic DT based cpufreq platdev driver"
> > >       help
> > >         This adds a generic DT based cpufreq platdev driver for frequency
> > >         management.  This creates a 'cpufreq-dt' platform device, on
> > > the
> > 
> > It seems that this new module is missing support for autoloading, causing issues
> > with CPUFREQ_DT=m.
> > 
> > Before that change, CPUFREQ_DT_PLATDEV ended up selected as =y. Now,
> > CPUFREQ_DT_PLATDEV ends up selected as =m. As it is not autoloaded, it means
> > that cpufreq-dt is not working anymore unless manually running "modprobe
> > cpufreq-dt-platdev".
> > 
> > Could you therefore please add support for autoloading?
> > 
> > Thanks,
> > Aurelien
> > 
> > --
> > Aurelien Jarno                          GPG: 4096R/1DDD8C9B
> > aurelien@...el32.net
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-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@...el32.net                     http://aurel32.net