On 08/12/2022 13:44, Howard-YH Hsu (許育豪) wrote:
On Wed, 2022-12-07 at 09:15 +0100, Nicolas Cavallari wrote:
On 07/12/2022 06:24, Howard Hsu wrote:
> This patch includes 3 changes:
> 1. The maximum throttle state can be set to 100 to fix the problem
> that
> thermal_protect_disable can never be triggered.
You are modifying the cooling_device part. The cooling_device is
explicitly configured to have a max state of
MT7915_CDEV_THROTTLE_MAX
(=99), so the thermal subsystem will probably prevent
mt7915_thermal_set_cur_throttle_state from being called with a
higher
value. It will also probably complain if get_cur_state starts
returning
values above MT7915_CDEV_THROTTLE_MAX.
And, as the comment below indicates, the thermal subsystem expect
that a
higher state provide more cooling. So if 99 means "maximum
cooling",
100 cannot mean "disable cooling".
Also, last time I tried, thermal_protect_disable didn't work; It
didn't
disable anything, the previous thermal throttle kept being applied.
Maybe a new firmware fixed this, but the kernel cannot simply expect
the
firmware to be up to date.
Thanks for your comments. Let me give you an example to confirm with
you if I understand your comments correctly.
1. The current cooling state of the cooling device is 50 (cur_state =
50).
2. The cooling state is set to 100 for "disable cooling".
3. The thermal subsystem decides to decrease state because the rest of
system is cooler. And then it will adjust it downward based on
cur_state, which is 100. For example, thermal subsytem set cur_state to
90. But obviously this will make the performance worse than at step 1,
even though the system is cooler. The design for 100 mean "disable
cooling" will mess up the thermal governor.
Let me know if there is any misunderstanding. And I will remove the
first change of this patch.
This is pretty much my second point.
The other case is if the system is overheating a lot and the kernel bumps the
state from e.g. 80 to 100, then the system should not disable throttling.
> 2. Throttle state do not need to be different from the previous
> state.
> This will make it is impossible for users to just change the
> trigger/restore temp but not the throttle state.
The throttle state is mostly set by the kernel's thermal governor
and
the user has only very little control over it. The thermal governor
runs every X seconds and will change the state if it thinks it is
too
low or too high.
The default step_wise governor will aggressively set it to zero if
the
system isn't overheating, for example.
I don't think there is any conflict between your comment and second
change. If we keep the check that previous cooling state shall be
different from the new cooling state, this will bother users who only
wants to change the temp1_crit but not the cur_state. It is
unreasonable for the user, if they wants the new temp1_crit to take
effect in the firmware, they must set a differnt cooling state.
The point I wanted to make is that the kernel sets the throttle state a lot, and
I assumed that it could also do it even if the state does not change, which
would send unnecessary mcu commands. But it's apparently not the case.
Also, if the user changes temp1_crit or temp1_max, the changes should probably
be applied immediately instead of expecting the user to change the state afterward.
