Re: [PATCH 2/2] PM / devfreq: add Airoha SoC devfreq driver

[Christian Marangi (Ansuel)]

Il giorno lun 17 ago 2026 alle ore 09:46 Krzysztof Kozlowski
<krzk@xxxxxxxxxx> ha scritto:
>
> On Mon, Aug 10, 2026 at 04:30:55PM +0200, Christian Marangi wrote:
> > Add simple Airoha SoC devfreq driver. This simple driver register a
> > driver from a given clock and register a passive governor to scale the
> > frequency with the CPU frequency.
> >
> > required-opp on the CPU frequency will be used to correctly bind the
> > clock to the related CPU frequency.
> >
> > GSW, NPU, SOE, BUS and many other clock will register this devfreq
> > driver to scale all these internal peripheral  from idle to performance
> > mode.
> >
> > Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
> > ---
> >  drivers/devfreq/Kconfig          | 10 ++++
> >  drivers/devfreq/Makefile         |  1 +
> >  drivers/devfreq/airoha-devfreq.c | 99 ++++++++++++++++++++++++++++++++
> >  3 files changed, 110 insertions(+)
> >  create mode 100644 drivers/devfreq/airoha-devfreq.c
> >
> > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> > index c999c4a1e567..1e857a7e9caf 100644
> > --- a/drivers/devfreq/Kconfig
> > +++ b/drivers/devfreq/Kconfig
> > @@ -75,6 +75,16 @@ config DEVFREQ_GOV_PASSIVE
> >
> >  comment "DEVFREQ Drivers"
> >
> > +config ARM_AIROHA_DEVFREQ
> > +     tristate "Scaling support for Airoha SoC"
> > +     depends on ARCH_AIROHA || COMPILE_TEST
> > +     select DEVFREQ_GOV_PASSIVE
> > +     help
> > +       This adds the DEVFREQ driver for the Airoha SoC.
> > +
> > +       The driver register with the cpufreq notifier and find the right frequency
> > +       based on the required OPP set in DT.
> > +
> >  config ARM_EXYNOS_BUS_DEVFREQ
> >       tristate "ARM Exynos Generic Memory Bus DEVFREQ Driver"
> >       depends on ARCH_EXYNOS || COMPILE_TEST
> > diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> > index 404179d79a9d..5ca27684dee3 100644
> > --- a/drivers/devfreq/Makefile
> > +++ b/drivers/devfreq/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)   += governor_userspace.o
> >  obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)    += governor_passive.o
> >
> >  # DEVFREQ Drivers
> > +obj-$(CONFIG_ARM_AIROHA_DEVFREQ)     += airoha-devfreq.o
> >  obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
> >  obj-$(CONFIG_ARM_HISI_UNCORE_DEVFREQ)        += hisi_uncore_freq.o
> >  obj-$(CONFIG_ARM_IMX_BUS_DEVFREQ)    += imx-bus.o
> > diff --git a/drivers/devfreq/airoha-devfreq.c b/drivers/devfreq/airoha-devfreq.c
> > new file mode 100644
> > index 000000000000..cb6d8b49e4a4
> > --- /dev/null
> > +++ b/drivers/devfreq/airoha-devfreq.c
> > @@ -0,0 +1,99 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/init.h>
> > +#include <linux/module.h>
> > +#include <linux/cpufreq.h>
> > +#include <linux/devfreq.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/clk.h>
> > +#include <linux/slab.h>
> > +#include <linux/pm_opp.h>
> > +
> > +struct airoha_devfreq_data {
> > +     struct clk *clk;
> > +
> > +     struct devfreq_passive_data gov_data;
> > +};
> > +
> > +static int airoha_devfreq_get_cur_freq(struct device *dev, unsigned long *freq)
> > +{
> > +     struct airoha_devfreq_data *data = dev_get_drvdata(dev);
> > +
> > +     *freq = clk_get_rate(data->clk);
> > +
> > +     return 0;
> > +};
> > +
> > +static int airoha_devfreq_target(struct device *dev, unsigned long *freq,
> > +                              u32 flags)
> > +{
> > +     struct airoha_devfreq_data *data = dev_get_drvdata(dev);
> > +
> > +     return clk_set_rate(data->clk, *freq);
> > +};
>
> Some odd copy-paste.
>
> Anyway, your driver is heavily incomplete. You can scale the clock
> directly from each device driver (each should register devfreq). You do
> not need completely new driver for that.
>

I sent a v2, the thing is that those subsystems need to scale with the
CPU frequency. It's not something where driver configure a static frequency.

There is a specific governor for devfreq driver that follow the CPU cpufreq
OPP call and with the help of DT required-opp, each subsystem is scaled
to the frequency.

It's to handle idle state for power saving and temperature and scale to
"turbo" when the SoC needs the extra perf.