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 <nicolas.cavallari@xxxxxxxxxxxxxxxxxxxxxxx>
---
drivers/net/wireless/mediatek/mt76/mt7915/init.c | 16 ++++++++++------
.../net/wireless/mediatek/mt76/mt7915/mt7915.h | 2 ++
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
index 2bc9097c5214..d6efbf1a2724 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
@@ -97,7 +97,7 @@ static int
mt7915_thermal_get_max_throttle_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
- *state = MT7915_THERMAL_THROTTLE_MAX;
+ *state = MT7915_CDEV_THROTTLE_MAX;
return 0;
}
@@ -108,7 +108,7 @@ mt7915_thermal_get_cur_throttle_state(struct thermal_cooling_device *cdev,
{
struct mt7915_phy *phy = cdev->devdata;
- *state = phy->throttle_state;
+ *state = phy->cdev_state;
return 0;
}
@@ -120,20 +120,24 @@ mt7915_thermal_set_cur_throttle_state(struct thermal_cooling_device *cdev,
struct mt7915_phy *phy = cdev->devdata;
int ret;
- if (state > MT7915_THERMAL_THROTTLE_MAX)
+ if (state > MT7915_CDEV_THROTTLE_MAX)
return -EINVAL;
if (phy->throttle_temp[0] > phy->throttle_temp[1])
return 0;
- if (state == phy->throttle_state)
+ if (state == phy->cdev_state)
return 0;
- ret = mt7915_mcu_set_thermal_throttling(phy, state);
+ // cooling_device convention: 0 = no cooling, more = more cooling
+ // mcu convention: 1 = max cooling, more = less cooling
+ ret = mt7915_mcu_set_thermal_throttling(phy,
+ MT7915_THERMAL_THROTTLE_MAX
+ - state);
if (ret)
return ret;
- phy->throttle_state = state;
+ phy->cdev_state = state;
return 0;
}
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h b/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
index 0403912a521d..cf4c8d2dcc60 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
@@ -49,6 +49,7 @@
#define MT7915_CFEND_RATE_11B 0x03 /* 11B LP, 11M */
#define MT7915_THERMAL_THROTTLE_MAX 100
+#define MT7915_CDEV_THROTTLE_MAX 99
#define MT7915_SKU_RATE_NUM 161
@@ -218,6 +219,7 @@ struct mt7915_phy {
struct ieee80211_vif *monitor_vif;
struct thermal_cooling_device *cdev;
+ u8 cdev_state;
u8 throttle_state;
u32 throttle_temp[2]; /* 0: critical high, 1: maximum */
--
2.34.1
