Messages in this thread | | | Date | Mon, 28 Feb 2022 13:21:30 +0100 | Subject | Re: Testing the thermal genetlink API | From | Daniel Lezcano <> |
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Hi Nicolas,
thanks for using the netlink and giving those feedbacks even you are unhappy with them.
On 28/02/2022 12:03, Nicolas Cavallari wrote: > I've played a bit with the thermal netlink interface and it wasn't pleasant: > > 1. The way attributes are used is painful. Instead of using arrays of > nested structs-like, it flattens them into a big nested attr where > you have to guess when an entry starts and when it ends. > libnl provides no helper for this case: > > [{nla_type=TZ|F_NESTED}, > [{nla_type=TZ_ID}, 1] > [{nla_type=TZ_NAME}, "name1"] > [{nla_type=TZ_ID}, 2] > [{nla_type=TZ_NAME}, "name2"] > [{nla_type=TZ_ID}, 3] > [{nla_type=TZ_NAME}, "name3"] > [{nla_type=TZ_ID}, 4] > [{nla_type=TZ_NAME}, "name4"] > ] > > 2. The genl_cmd types are not unique between multicast events and > command replies. If you send genl_cmd=3 (CMD_TZ_GET_TEMP) and you > get a genl_cmd=3 reply, you cannot know if it is a CMD_TZ_GET_TEMP > response or a EVENT_TZ_DISABLE because both have genl_cmd=3, but > completely different semantics. > 3. The API is heavy. Getting the complete information about all thermal > zones requires 1 + 6 * thermal_zones netlink requests, each of them > only returning few information. You need most of them to merely > translate the event's TZ_ID/TZ_TRIP_ID/CDEV_ID to names.
That is part of the discovery and it should happen only once when you get the thermal information.
> 4. THERMAL_GENL_CMD_TZ_GET_TRIP cause an oops if the thermal zone driver > does not have a get_trip_hyst callback. > This concerns all drivers, short of two. A patch follows.
Great, thanks for the fix.
> For the record, I couldn't find any open source program using this API. > It's also not enabled in all distributions.
The netlink support is very recent. A library has been posted [1] and hopefully it can helps you to get rid of all the complexity.
Thanks for testing
-- D.
[1] https://lore.kernel.org/all/20220218125334.995447-1-daniel.lezcano@linaro.org/
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