Hi,
On Sun, 2013-10-20 at 12:23 -0700, Guenter Roeck wrote:
> On 10/20/2013 11:10 AM, Arnaud Ebalard wrote:
> > Hi,
> >
> > With 3.12-rc series, sysfs support for thermal susbsytem (and/or hwmon
> > one) was modified in such a way that sensors utility (current 3.3.4
> > version with 3.3.4 version of libsensors from lm-sensors package on
> > Debian unstable) does not see the temperature sensor anymore on armada
> > 370 platforms (not tested on others). Additionally, the changes break
> > existing configurations of fancontrol utility, which prevents the
> > fan to be regulated correctly w/o recreating an /etc/fancontrol w/
> > pwmconfig.
> >
> > Here is what I have on my Armada 370-based system on a 3.11.5:
> >
> > # sensors
> > g762-i2c-0-3e
> > Adapter: mv64xxx_i2c adapter
> > fan1: 2457 RPM (div = 1)
> >
> > armada_thermal-virtual-0
> > Adapter: Virtual device
> > temp1: +45.7°C
> >
> > And what I get on 3.12-rc6:
> >
> > # sensors
> > g762-i2c-0-3e
> > Adapter: mv64xxx_i2c adapter
> > fan1: 1350 RPM (div = 1)
> >
> >
> > Monitoring what sensors does w/ strace, I started looking at the changes
> > to /sys/class/hwmon/hwmon1/:
> >
> > On 3.11.5:
> >
> > # find /sys/class/hwmon/hwmon1/
> > /sys/class/hwmon/hwmon1/
> > /sys/class/hwmon/hwmon1/name
> > /sys/class/hwmon/hwmon1/subsystem
> > /sys/class/hwmon/hwmon1/uevent
> > /sys/class/hwmon/hwmon1/temp1_input
> >
> > On 3.12-rc6:
> >
> > # find /sys/class/hwmon/hwmon1/
> > /sys/class/hwmon/hwmon1/
> > /sys/class/hwmon/hwmon1/name
> > /sys/class/hwmon/hwmon1/device
> > /sys/class/hwmon/hwmon1/subsystem
> > /sys/class/hwmon/hwmon1/uevent
> > /sys/class/hwmon/hwmon1/temp1_input
> >
> > # find /sys/class/hwmon/hwmon1/device/
> > /sys/class/hwmon/hwmon1/device/
> > /sys/class/hwmon/hwmon1/device/temp
> > /sys/class/hwmon/hwmon1/device/type
> > /sys/class/hwmon/hwmon1/device/hwmon1
> > /sys/class/hwmon/hwmon1/device/hwmon1/name
> > /sys/class/hwmon/hwmon1/device/hwmon1/device
> > /sys/class/hwmon/hwmon1/device/hwmon1/subsystem
> > /sys/class/hwmon/hwmon1/device/hwmon1/uevent
> > /sys/class/hwmon/hwmon1/device/hwmon1/temp1_input
> > /sys/class/hwmon/hwmon1/device/subsystem
> > /sys/class/hwmon/hwmon1/device/policy
> > /sys/class/hwmon/hwmon1/device/uevent
> > /sys/class/hwmon/hwmon1/device/passive
> >
> > Is that expected? As for sensors, it *seems* to be bothered to find a
> > device/ folder in /sys/class/hwmon/hwmon1/ w/o no name entry in it.
> >
I agree. And it should be caused by this commit.
commit b82715fdd4a5407f56853b24d387d484dd9c3b5b
Author: Eduardo Valentin <eduardo.valentin@xxxxxx>
Date: Fri Aug 23 17:07:58 2013 -0400
drivers: thermal: parent virtual hwmon with thermal zone
When creating virtual hwmon devices based out of thermal
zone devices, the virtual devices won't have parents.
This patch changes the code so that the parent of virtual
hwmon devices is the thermal zone device that they are
based of.
Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxx>
>
> The 'name' attribute should not be the problem, since there is a 'name'
> attribute in the /sys/class/hwmon/hwmon1/ directory.
>
> Key difference is that there is now a 'device' subdirectory,
Right.
> which results
> in different handling by libsensors;
Oh, I'm not aware of this before.
There is no such statement in the comments of hwmon_device_register(),
or anywhere else.
Could you show me some tutorials about how the sysfs I/F misleads
libsensors?
But anyway, I will revert this patch first.
Thanks for reporting the problem, Arnaud!
thanks,
rui
> the entry is no longer a virtual entry
> but is expected to have a real device attached to it. For this device,
> libsensors tries to scan the 'subsystem' entry which in turn must be well
> defined and known. My suspicion is that the reported subsystem may not be
> recognized by libsensors.
>
> One question is why there is now a device entry, even though this is still as
> virtual as it was before. You'll have to ask the thermal subsystem maintainers
> for an answer.
> I am also concerned about the 'hwmon1' subdirectory underneath hwmon1/device;
> that suggests that hwmon1 may be declared to be a child of itself, which would
> obviously not be a good idea.
>
> Also, note that the thermal subsystem creates (or may create) sensor attributes
> after registering the hwmon device, which means you can not rely on the udev
> event that comes with the hwmon device creation and assume that all sensor
> attributes exist at that time. I don't currently know how to handle this situation.
> This is not unique, though; the coretemp driver does the same. Just something
> to keep in mind.
>
> Guenter
>
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