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[v4,0/3] thermal/netlink/intel_hfi: Enable HFI feature only when required

Message ID 20240223155942.60813-1-stanislaw.gruszka@linux.intel.com
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Series thermal/netlink/intel_hfi: Enable HFI feature only when required | expand

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Stanislaw Gruszka Feb. 23, 2024, 3:59 p.m. UTC 
The patchset is based on

 https://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux.git
 for-thermal-genetlink-family-bind-unbind-callbacks

and implement genetlink family bind/unbind callbacks in thermal-netlink and
add notifications to thermal subdrivers. Those willh allow drivers to send
netlink multicast events based on the presence of actual user-space consumers.
This functionality optimizes resource usage by allowing disabling
of features when not needed.

Then implement the notification mechanism in the intel_hif driver,
it is utilized to disable the Hardware Feedback Interface (HFI)
dynamically. By implementing a thermal genl notify callback, the driver
can now enable or disable the HFI based on actual demand, particularly
when user-space applications like intel-speed-select or Intel Low Power
daemon utilize events related to performance and energy efficiency
capabilities.

On machines where Intel HFI is present, but there are no user-space
components installed, we can save tons of CPU cycles.

Changes v4 -> v5:

- Fix hif vs. hfi in the changelog
- Rename thermal_gnl_chain
- Add new patch with rename of thermal_gnl_family
- Fix syscore concurrency comment
- Remove unneeded hfi_instance variable
- Rename hfi_do_enable/disable
- Avoid multiple enabling 
- Add comment about registering for events before they can be generated
- Rename hfi_thermal_clients_num since later there will be KVM clients

Changes v3 -> v4:

- Add 'static inline' in patch2

Changes v2 -> v3:

- Fix unused variable compilation warning
- Add missed Suggested by tag to patch2
 
Changes v1 -> v2:

- Rewrite using netlink_bind/netlink_unbind callbacks.

- Minor changelog tweaks.

- Add missing check in intel hfi syscore resume (had it on my testing,
but somehow missed in post).

- Do not use netlink_has_listeners() any longer, use custom counter instead.
To keep using netlink_has_listners() would be required to rearrange 
netlink_setsockopt() and possibly netlink_bind() functions, to call 
nlk->netlink_bind() after listeners are updated. So I decided to custom
counter. This have potential issue as thermal netlink registers before
intel_hif, so theoretically intel_hif can miss events. But since both
are required to be kernel build-in (if CONFIG_INTEL_HFI_THERMAL is
configured), they start before any user-space.

v1: https://lore.kernel.org/linux-pm/20240131120535.933424-1-stanislaw.gruszka@linux.intel.com//
v2: https://lore.kernel.org/linux-pm/20240206133605.1518373-1-stanislaw.gruszka@linux.intel.com/
v3: https://lore.kernel.org/linux-pm/20240209120625.1775017-1-stanislaw.gruszka@linux.intel.com/
v4: https://lore.kernel.org/linux-pm/20240212161615.161935-1-stanislaw.gruszka@linux.intel.com/


*** BLURB HERE ***

Stanislaw Gruszka (3):
  thermal: netlink: Add genetlink bind/unbind notifications
  thermal: netlink: Rename thermal_gnl_family
  thermal: intel: hfi: Enable interface only when required

 drivers/thermal/intel/intel_hfi.c | 97 ++++++++++++++++++++++++++++---
 drivers/thermal/thermal_netlink.c | 62 +++++++++++++++-----
 drivers/thermal/thermal_netlink.h | 26 +++++++++
 3 files changed, 161 insertions(+), 24 deletions(-)