Re: thermal: uevent/netlink with step_wise?

[Brian Norris <computersforpeace@gmail.com>]

On Tue, Mar 31, 2015 at 03:43:48PM -0700, Brian Norris wrote:
> Particularly, I'm looking right now at using the uevent/netlink
> notification mechanism. It seems that this is only active when we use
> the 'user_space' governor, meaning I can't get any user-space
> notifications when using the in-kernel governor. Am I missing something,
> or is this a known limitation? Is there any reason we can't enable both?
> For the user-space side, I'd mostly be interested in being a consumer;
> e.g., display warnings in high-temperature scenarios; although I might
> also use it to trigger some user-space cooling mechanisms.

I'm noticing two additional interesting details.

1. There's a separate netlink event mechanism that has never been used.
See generate_netlink_event(), from this commit:

commit 4cb18728709683c91a5f6f8d5f337bfb498b089a
Author: R.Durgadoss <durgadoss.r@intel.com>
Date:   Wed Oct 27 03:33:29 2010 +0530

    thermal: Add event notification to thermal framework

2. The Samsung Exynos thermal driver reports uevent info directly, no
matter which governor is in use. See exynos_report_trigger(). Is it
acceptable to augment drivers in this way, or wouldn't it make more
sense to improve the core framework to support this type of
notification?

Brian