mirror of
https://github.com/outbackdingo/mt76.git
synced 2026-10-24 13:26:48 +00:00
Nicolas CavallariandFelix Fietkau
9fee8f3736
mt7915e registers a cooling_device with wrong semantics: 1. cooling_device expect that higher states values should cool more, but mt7915e did the opposite... with the exception of state == 0, which should "disable thermal management", but does not seem to have any effect since the previous state is kept. The result is that when the thermal zone heats up a bit and bumps the cooling_device state from 0 to 1 to cool a bit, the performance is destroyed, and when going back from 1 to 0, the performance stays bad. 2. Reading the cooling_device state does not always return the last written state, but can return the actual hardware throttle state, which is different. This is a problem because the mt7915 firmware actually implement the equivalent of a thermal zone with trip points. Setting the cooling device state actually changes the throttles at each trip point, so the following could occur if the first issue is fixed: - thermal subsystem set state to 100% power (state=0) - mt7915e driver set trip throttles to [100%, 50%, 25%, 12%] - hardware heats up and decides to switch to 50% power - thermal subsystem see that power is 50% (state=50), decide to increase it to 60% (state=40) because the rest of the system is cool. - mt7915e driver set trip throttle to [60%, 30%, 15%, 7%] - hardware thus switches to 30% power [race to the bottom continues...] This patch corrects the semantics of the cooling_device to the one that the thermal subsystem expect it. Signed-off-by: Nicolas Cavallari <[email protected]> Signed-off-by: Felix Fietkau <[email protected]>