Re: [PATCH 06/16] hwmon: tmp102: expose to thermal fw via DT nodes

[Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>]

On Wed, Sep 18, 2013 at 11:54:18AM -0400, Eduardo Valentin wrote:
> On 18-09-2013 11:17, Guenter Roeck wrote:
> > On Wed, Sep 18, 2013 at 10:29:09AM -0400, Eduardo Valentin wrote:
> >> On 18-09-2013 07:18, Guenter Roeck wrote:
> >>> On Tue, Sep 17, 2013 at 06:29:45PM -0400, Eduardo Valentin wrote:
> >>>> On 15-09-2013 19:33, Guenter Roeck wrote:
> >>>>> On 09/15/2013 03:02 PM, Eduardo Valentin wrote:
> >>>>>> This patch adds to tmp102 temperature sensor the possibility to
> >>>>>> expose itself as thermal zone device, registered on the thermal
> >>>>>> framework.
> >>>>>>
> >>>>>> The thermal zone is built only if a device tree node describing
> >>>>>> a thermal zone for this sensor is present inside the tmp102 DT
> >>>>>> node. Otherwise, the driver behavior will be the same.
> >>>>>>
> >>>>>> Cc: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> Cc: Guenter Roeck
> >>>>>> <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Cc: lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org Cc:
> >>>>>> linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Signed-off-by: Eduardo Valentin
> >>>>>> <eduardo.valentin-l0cyMroinI0@public.gmane.org> --- drivers/hwmon/tmp102.c | 28
> >>>>>> ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
> >>>>>>
> >>>>>> diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c 
> >>>>>> index d7b47ab..e432444 100644 --- a/drivers/hwmon/tmp102.c +++
> >>>>>> b/drivers/hwmon/tmp102.c @@ -27,6 +27,8 @@ #include
> >>>>>> <linux/mutex.h> #include <linux/device.h> #include
> >>>>>> <linux/jiffies.h> +#include <linux/thermal.h> +#include
> >>>>>> <linux/of.h>
> >>>>>>
> >>>>>> #define    DRIVER_NAME "tmp102"
> >>>>>>
> >>>>>> @@ -50,6 +52,7 @@
> >>>>>>
> >>>>>> struct tmp102 { struct device *hwmon_dev; +    struct
> >>>>>> thermal_zone_device *tz; struct mutex lock; u16 config_orig; 
> >>>>>> unsigned long last_update; @@ -93,6 +96,19 @@ static struct
> >>>>>> tmp102 *tmp102_update_device(struct i2c_client *client) return
> >>>>>> tmp102; }
> >>>>>>
> >>>>>> +static int tmp102_read_temp(void *dev, long *temp) +{ +
> >>>>>> struct tmp102 *tmp102 =
> >>>>>> tmp102_update_device(to_i2c_client(dev)); + +    if
> >>>>>> (tmp102->temp[0] < 0) +        dev_warn(tmp102->hwmon_dev, +
> >>>>>> "operating in negative temp: %d\n", tmp102->temp[0]); +
> >>>>>
> >>>>> Please drop this warning.
> >>>>>
> >>>>
> >>>> Done for both drivers.
> >>>>
> >>>>> Guenter
> >>>>>
> >>>>>> +    *temp = tmp102->temp[0]; + +    return 0; +} + static
> >>>>>> ssize_t tmp102_show_temp(struct device *dev, struct
> >>>>>> device_attribute *attr, char *buf) @@ -204,6 +220,16 @@ static
> >>>>>> int tmp102_probe(struct i2c_client *client, goto
> >>>>>> fail_remove_sysfs; }
> >>>>>>
> >>>>>> +    tmp102->tz = thermal_zone_of_sensor_register(&client->dev,
> >>>>>> 0, +                             &client->dev, +
> >>>>>> tmp102_read_temp, NULL); +    if (IS_ERR(tmp102->tz)) { +
> >>>>>> dev_warn(&client->dev, +             "Could not parse thermal
> >>>>>> data in device tree: %ld\n", +
> >>>>>> PTR_ERR(tmp102->tz));
> >>>>>
> >>>>> Please drop this warning. You already create error messages in 
> >>>>> thermal_zone_of_sensor_register(). That should be sufficient. The
> >>>>> same applies to the lm75 patch.
> >>>>
> >>>> OK. Done for both.
> >>>>
> >>>>>
> >>>>> As a side note, I would suggest to provide devm_ functions for 
> >>>>> registration. We are introducing those for hwmon registration,
> >>>>> which enables us to remove most _remove functions. It would be
> >>>>> great if we can keep it that way.
> >>>>>
> >>>>
> >>>> Right. This side note is taken. Actually this is on my todo list
> >>>> for quite a while. But I believe this should not block this series,
> >>>> should it? I will be probably cleaning the thermal framework code
> >>>> after this current work is accepted at least.
> >>>>
> >>>>> On a higher level, I don't think it is a good idea to make
> >>>>> thermal zones and thermal zone data mandatory. Many systems may
> >>>>> neither need nor want it.
> >>>>>
> >>>>
> >>>> Well, I agree with you. Did you see something hard required in the
> >>>> patch I sent. I made it so that it could continue the driver probe
> >>>> without thermal zones, as you requested.
> >>>>
> >>> If it is not mandatory you should not dump an error message to the
> >>> console in the thermal registration function. Since you do, you at
> >>> least consider it mandatory if that function is called.
> >>>
> >>> So please either drop the error message from the registration
> >>> function or add a check into the drivers to only register into the
> >>> thermal subsystem if there is a respective thermal entry for that
> >>> sensor in the devicetree data.
> >>>
> >>> There are systes out there with literally dozens of temperature
> >>> sensors. In many cases, those are purely for system health
> >>> monitoring, not for thermal management. I don't want to end up in a
> >>> situation where users complain about dozens of error messages on the
> >>> console and no way to avoid it but providing dummy thermal subsystem
> >>> data.
> >>>
> >>
> >> Now I see.
> >>
> >>
> >> Then I will rollback to the previous version in which lm sensors were
> >> first probing for thermal properties within their dt node. Something like:
> >> diff --git a/drivers/hwmon/tmp102.c b/drivers/hwmon/tmp102.c
> >> index dc96598..cb1c663 100644
> >> --- a/drivers/hwmon/tmp102.c
> >> +++ b/drivers/hwmon/tmp102.c
> >> @@ -216,11 +216,13 @@ static int tmp102_probe(struct i2c_client *client,
> >>                 goto fail_remove_sysfs;
> >>         }
> >>
> >> -       tmp102->tz = thermal_zone_of_sensor_register(&client->dev, 0,
> >> -                                                    &client->dev,
> >> -                                                    tmp102_read_temp,
> >> NULL);
> >> -       if (IS_ERR(tmp102->tz))
> >> -               tmp102->tz = NULL;
> >> +       if ((of_find_property(client->dev.of_node, "#sensor-cells", NULL)) {
> >> +               tmp102->tz =
> >> thermal_zone_of_sensor_register(&client->dev, 0,
> >> +                                                            &client->dev,
> >> +
> >> tmp102_read_temp, NULL);
> >> +               if (IS_ERR(tmp102->tz))
> >> +                       tmp102->tz = NULL;
> >> +       }
> >>
> >>         dev_info(&client->dev, "initialized\n");
> >>
> >>
> >> Does it sound reasonable?
> >>
> > Personally I would prefer if the registration code fails silently.
> > Pushing the above code into each driver is just adding the same code
> > repeatedly all over the place.
> 
> Fair enough. It becomes tedious and just duplicating code. I agree.
> 
> So I will keep the v2 I just sent and remove the annoying error messages
> from of-thermal.c while registering the sensors.
> 
> > 
> > Also, each sensor instance will still result in an error if there
> > is no global "thermal-zones" entry. Checking for that global entry
> > in each driver would be even more excessive, and I just don't like
> > that noisyness.
> > 
> > Also, I think you'll need to create devicetree bindings documents
> > for the two sensors.
> > 
> 
> Why would I? There is only one extra property and that is already
> documented. I think the sensor still falls into the dummy dt node.
> 
I'll leave that up to the devicetree folks to decide.

Guenter
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