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Date: Fri, 25 Feb 2022 15:02:27 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Benjamin Li <benl@...areup.com>, Amit Kucheria <amitk@...nel.org>,
Thara Gopinath <thara.gopinath@...aro.org>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>,
Zac Crosby <zac@...areup.com>, Andy Gross <agross@...nel.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Zhang Rui <rui.zhang@...el.com>, linux-arm-msm@...r.kernel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] drivers: thermal: tsens: respect thermal_device_mode
in threshold irq reporting
On 20/01/2022 21:01, Benjamin Li wrote:
> 'echo disabled > .../thermal_zoneX/mode' will disable the thermal core's
> polling mechanism to check for threshold trips. This is used sometimes to
> run performance test cases.
>
> However, tsens supports an interrupt mechanism to receive notification of
> trips, implemented in commit 634e11d5b450 ("drivers: thermal: tsens: Add
> interrupt support").
>
> Currently the thermal zone mode that's set by userspace is not checked
> before propagating threshold trip events from IRQs. Let's fix this to
> restore the abilty to disable thermal throttling at runtime.
>
> ====================
>
> Tested on MSM8939 running 5.16.0. This platform has 8 cores; the first
> four thermal zones control cpu0-3 and the last zone is for the other four
> CPUs together.
>
> for f in /sys/class/thermal/thermal_zone*; do
> echo "disabled" > $f/mode
> echo $f | paste - $f/type $f/mode
> done
>
> /sys/class/thermal/thermal_zone0 cpu0-thermal disabled
> /sys/class/thermal/thermal_zone1 cpu1-thermal disabled
> /sys/class/thermal/thermal_zone2 cpu2-thermal disabled
> /sys/class/thermal/thermal_zone3 cpu3-thermal disabled
> /sys/class/thermal/thermal_zone4 cpu4567-thermal disabled
>
> With mitigation thresholds at 75 degC and load running, we can now cruise
> past temp=75000 without CPU throttling kicking in.
>
> watch -n 1 "grep '' /sys/class/thermal/*/temp
> /sys/class/thermal/*/cur_state
> /sys/bus/cpu/devices/cpu*/cpufreq/cpuinfo_cur_freq"
>
> /sys/class/thermal/thermal_zone0/temp:82000
> /sys/class/thermal/thermal_zone1/temp:84000
> /sys/class/thermal/thermal_zone2/temp:87000
> /sys/class/thermal/thermal_zone3/temp:84000
> /sys/class/thermal/thermal_zone4/temp:84000
> /sys/class/thermal/cooling_device0/cur_state:0
> /sys/class/thermal/cooling_device1/cur_state:0
> /sys/bus/cpu/devices/cpu0/cpufreq/cpuinfo_cur_freq:1113600
> /sys/bus/cpu/devices/cpu1/cpufreq/cpuinfo_cur_freq:1113600
> /sys/bus/cpu/devices/cpu2/cpufreq/cpuinfo_cur_freq:1113600
> /sys/bus/cpu/devices/cpu3/cpufreq/cpuinfo_cur_freq:1113600
> /sys/bus/cpu/devices/cpu4/cpufreq/cpuinfo_cur_freq:800000
> /sys/bus/cpu/devices/cpu5/cpufreq/cpuinfo_cur_freq:800000
> /sys/bus/cpu/devices/cpu6/cpufreq/cpuinfo_cur_freq:800000
> /sys/bus/cpu/devices/cpu7/cpufreq/cpuinfo_cur_freq:800000
>
> Reported-by: Zac Crosby <zac@...areup.com>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> Signed-off-by: Benjamin Li <benl@...areup.com>
> ---
> Changes in v3:
> - Upgraded logging to dev_info_ratelimited and revised log message.
> - Remove unrelated hunk.
>
> Some drivers that support thermal zone disabling implement a set_mode
> operation and simply disable the sensor or the relevant IRQ(s), so they
> actually don't log anything when zones are disabled. These drivers are
> imx_thermal.c, intel_quark_dts_thermal.c, and int3400_thermal.c.
>
> For tsens.c, implementing a change_mode would require migrating the driver
> from devm_thermal_zone_of_sensor_register to thermal_zone_device_register
> (or updating thermal_of.c to add a change_mode operation in thermal_zone_
> of_device_ops).
>
> stm_thermal.c seems to use this patch's model of not disabling IRQs when
> the zone is disabled (they still perform the thermal_zone_device_update
> upon IRQ, but return -EAGAIN from their get_temp).
What is the concern by changing the core code to have a correct handling
of the disabled / enabled state in this driver ? (and by this way give
the opportunity to other drivers to fix their code)
> Changes in v2:
> - Reordered sentences in first part of commit message to make sense.
>
> drivers/thermal/qcom/tsens.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c
> index 99a8d9f3e03c..dd0002829536 100644
> --- a/drivers/thermal/qcom/tsens.c
> +++ b/drivers/thermal/qcom/tsens.c
> @@ -509,10 +509,14 @@ static irqreturn_t tsens_irq_thread(int irq, void *data)
> spin_unlock_irqrestore(&priv->ul_lock, flags);
>
> if (trigger) {
> - dev_dbg(priv->dev, "[%u] %s: TZ update trigger (%d mC)\n",
> - hw_id, __func__, temp);
> - thermal_zone_device_update(s->tzd,
> - THERMAL_EVENT_UNSPECIFIED);
> + if (s->tzd->mode == THERMAL_DEVICE_ENABLED) {
> + dev_dbg(priv->dev, "[%u] %s: TZ update trigger (%d mC)\n",
> + hw_id, __func__, temp);
> + thermal_zone_device_update(s->tzd, THERMAL_EVENT_UNSPECIFIED);
> + } else {
> + dev_info_ratelimited(priv->dev, "[%u] %s: TZ update trigger (%d mC) skipped - zone disabled, operating outside of safety limits!\n",
> + hw_id, __func__, temp);
> + }
> } else {
> dev_dbg(priv->dev, "[%u] %s: no violation: %d\n",
> hw_id, __func__, temp);
--
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