On 05/16/2018 11:10 PM, Shilpasri G Bhat wrote:

On 05/15/2018 08:32 PM, Guenter Roeck wrote:
On Thu, Mar 22, 2018 at 04:24:32PM +0530, Shilpasri G Bhat wrote:
This patch series adds support to enable/disable OCC based
inband-sensor groups at runtime. The environmental sensor groups are
managed in HWMON and the remaining platform specific sensor groups are
managed in /sys/firmware/opal.

The firmware changes required for this patch is posted below:

Sorry for not getting back earlier. This is a tough one.

Thanks for the reply. I have tried to answer your questions according to my
understanding below:

Key problem is that you are changing the ABI with those new attributes.
On top of that, the attributes _do_ make some sense (many chips support
enabling/disabling of individual sensors), suggesting that those or
similar attributes may or even should at some point be added to the ABI.

At the same time, returning "0" as measurement values when sensors are
disabled does not seem like a good idea, since "0" is a perfectly valid
measurement, at least for most sensors.

I agree.

Given that, we need to have a discussion about adding _enable attributes to
the ABI

what is the scope,
IIUC the scope should be RW and the attribute is defined for each supported
sensor group

That is _your_ need. I am not aware of any other chip where a per-sensor group
attribute would make sense. The discussion we need has to extend beyond the need
of a single chip.


when should the attributes exist and when not,
We control this currently via device-tree

do we want/need power_enable or powerX_enable or both, and so on), and
We need power_enable right now

what to return if a sensor is disabled (such as -ENODATA).
-ENODATA sounds good.

Thanks and Regards,

  Once we have an
agreement, we can continue with an implementation.


Shilpasri G Bhat (3):
   powernv:opal-sensor-groups: Add support to enable sensor groups
   hwmon: ibmpowernv: Add attributes to enable/disable sensor groups
   powernv: opal-sensor-groups: Add attributes to disable/enable sensors

  .../ABI/testing/sysfs-firmware-opal-sensor-groups  |  34 ++++++
  Documentation/hwmon/ibmpowernv                     |  31 ++++-
  arch/powerpc/include/asm/opal-api.h                |   4 +-
  arch/powerpc/include/asm/opal.h                    |   2 +
  .../powerpc/platforms/powernv/opal-sensor-groups.c | 104 ++++++++++++-----
  arch/powerpc/platforms/powernv/opal-wrappers.S     |   1 +
  drivers/hwmon/ibmpowernv.c                         | 127 +++++++++++++++++++--
  7 files changed, 265 insertions(+), 38 deletions(-)
  create mode 100644 Documentation/ABI/testing/sysfs-firmware-opal-sensor-groups


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