From ec0d89150a9381d591344a9f6f5428655c227a7f Mon Sep 17 00:00:00 2001 From: Manaf Meethalavalappu Pallikunhi Date: Tue, 22 Sep 2026 17:49:02 +0530 Subject: [PATCH] thermal: gov_step_wise: Fix stale mitigation vote with non-zero lower bounds MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When two or more thermal zones bind to a common cooling device and one zone uses a non-zero instance->lower value, there is a bug where the instance holds a stale mitigation vote even after its trip is cleared. Problem scenario: - thermal-zone1: Trip at 50°C, cooling-map with lower=0 - thermal-zone2: Trip at 55°C, cooling-map with lower=2 - Both zones share the same cooling device (e.g., CPU) Issue flow: 1. Both trips trigger, zone1 requests state 5, zone2 also mitigates 2. Zone2 trip clears (temp < 53°C due to hysteresis) 3. When throttle=false and trend=THERMAL_TREND_DROPPING: - Current code checks: if (cur_state <= instance->lower) return THERMAL_NO_TARGET - Since cur_state (5) > instance->lower (2), it returns instance->lower (2) - This is the BUG where it returns instance->lower even though trip is cleared 4. Zone2's passive polling stops (tz->passive reaches 0) - no more updates for zone2 5. Zone2's stale vote of 2 persists indefinitely 6. Even when zone1 wants to reduce cooling to state, the cooling device cannot go below state 2 due to zone2's stale vote When a trip is cleared (throttle == false), always return THERMAL_NO_TARGET instead of instance->lower. Remove the unnecessary check comparing cur_state with instance->lower. Since passive polling is already deactivated when the trip is cleared, the instance should always be deactivated regardless of its current cooling state. This ensures that instances with non-zero lower bounds do not retain stale mitigation votes after their trips are cleared. Fixes: 042a3d80f118 ("thermal: core: Move passive polling management to the core") Signed-off-by: Manaf Meethalavalappu Pallikunhi Link: https://patch.msgid.link/20260922-step_wise_multi_zone_stale_vote_fix-v1-1-789f68dab229@oss.qualcomm.com Signed-off-by: Rafael J. Wysocki --- drivers/thermal/gov_step_wise.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/thermal/gov_step_wise.c b/drivers/thermal/gov_step_wise.c index ea277c466d8d..4fa4377f0d42 100644 --- a/drivers/thermal/gov_step_wise.c +++ b/drivers/thermal/gov_step_wise.c @@ -65,14 +65,12 @@ static unsigned long get_target_state(struct thermal_instance *instance, min(instance->lower + 1, instance->upper), instance->upper); } else if (trend == THERMAL_TREND_DROPPING) { - if (cur_state <= instance->lower) - return THERMAL_NO_TARGET; - /* - * If 'throttle' is false, no mitigation is necessary, so - * request the lower state for this instance. + * If 'throttle' is false, no mitigation is necessary and + * passive polling is already deactivated, so clear this + * instance state by returning THERMAL_NO_TARGET. */ - return instance->lower; + return THERMAL_NO_TARGET; } return instance->target;