Re: [PATCH v3 12/12] mfd: cros_ec: Add throttler sub-device

From: Enric Balletbo Serra <eballetbo@gmail.com>
To: Brian Norris <briannorris@chromium.org>
Cc: Matthias Kaehlcke <mka@chromium.org>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Linux PM list <linux-pm@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Doug Anderson <dianders@chromium.org>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	viresh.kumar@linaro.org, Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH v3 12/12] mfd: cros_ec: Add throttler sub-device
Date: Tue, 19 Jun 2018 10:41:01 +0200	[thread overview]
Message-ID: <CAFqH_520Z4nAkXsnKeO9ZGqSSfPg_7f7pjJs=t=ryQTBExfwoA@mail.gmail.com> (raw)
In-Reply-To: <20180618232109.GB154056@rodete-desktop-imager.corp.google.com>

Hi Matthias,

I am also interested on the answer of Brian comments :). One small comment.

Missatge de Brian Norris <briannorris@chromium.org> del dia dt., 19 de
juny 2018 a les 1:22:
>
> Hi,
>
> On Thu, Jun 14, 2018 at 12:47:12PM -0700, Matthias Kaehlcke wrote:
> > Instantiate the CrOS EC throttler if it is enabled in the kernel
> > configuration.
> >
> > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > ---
> > Changes in v3:
> > - patch added to series
> >
> >  drivers/mfd/cros_ec.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> > index 36156a41499c..5f52b6e2c21a 100644
> > --- a/drivers/mfd/cros_ec.c
> > +++ b/drivers/mfd/cros_ec.c
> > @@ -91,6 +91,10 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
> >       return cros_ec_cmd_xfer(ec_dev, &buf.msg);
> >  }
> >
> > +static const struct mfd_cell ec_throttler_cell = {
> > +     { .name = "cros-ec-throttler" }
> > +};
> > +

As Brian said I think that this should go in cros_ec_dev?

Even when only there is one cell we tend to use the array format (see
i.e the cros-ec-rtc and the others in cros_ec_dev).

+static const struct mfd_cell ec_throttler_cells[] = {
+     { .name = "cros-ec-throttler" }
+};

> >  int cros_ec_register(struct cros_ec_device *ec_dev)
> >  {
> >       struct device *dev = ec_dev->dev;
> > @@ -153,6 +157,18 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
> >               }
> >       }
> >
> > +     if (IS_ENABLED(CONFIG_CROS_EC_THROTTLER)) {
> > +             err = mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO,
> > +                                   &ec_throttler_cell, 1, NULL, ec_dev->irq,

ARRAY_SIZE(ec_throttler_cells)

> > +                                   NULL);
>
> Most of this similar sub-device registration seems to have moved to
> cros_ec_dev.c, in ec_device_probe(). Should this do the same?
>
> And on a similar note: is there a way to determine EC support for this
> feature (e.g., EC_FEATURE_*)? Or do we just have to listen for
> appropriate throttling events that may never come?
>
> Also, is this very useful on non-DT systems? Does this fail gracefully?
>
> Brian
>
> > +             if (err) {
> > +                     dev_err(dev,
> > +                             "Failed to register throttler subdevice %d\n",
> > +                             err);
> > +                     return err;
> > +             }
> > +     }
> > +
> >       if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> >               err = devm_of_platform_populate(dev);
> >               if (err) {
> > --
> > 2.18.0.rc1.242.g61856ae69a-goog
> >

Cheers,
 Enric