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SubjectRe: [PATCH 0/3] Add support to disable sensor groups in P9
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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:
>> https://lists.ozlabs.org/pipermail/skiboot/2018-March/010812.html
>>
>
> 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

> 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,
Shilpa

Once we have an
> agreement, we can continue with an implementation.
>
> Guenter
>
>> 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
>>
>> --
>> 1.8.3.1
>>
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