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cpufreq: qcom-cpufreq-hw: Revert adding cpufreq qos 

[ Upstream commit e2b47e5859 ]

The OSM/EPSS hardware controls the frequency of each CPU cluster based
on requests from the OS and various throttling events in the system.
While throttling is in effect the related dcvs interrupt will be kept
high. The purpose of the code handling this interrupt is to
continuously report the thermal pressure based on the throttled
frequency.

The reasoning for adding QoS control to this mechanism is not entirely
clear, but the introduction of commit 'c4c0efb06f17 ("cpufreq:
qcom-cpufreq-hw: Add cpufreq qos for LMh")' causes the
scaling_max_frequncy to be set to the throttled frequency. On the next
iteration of polling, the throttled frequency is above or equal to the
newly requested frequency, so the polling is stopped.

With cpufreq limiting the max frequency, the hardware no longer report a
throttling state and no further updates to thermal pressure or qos
state are made.

The result of this is that scaling_max_frequency can only go down, and
the system becomes slower and slower every time a thermal throttling
event is reported by the hardware.

Even if the logic could be improved, there is no reason for software to
limit the max freqency in response to the hardware limiting the max
frequency. At best software will follow the reported hardware state, but
typically it will cause slower backoff of the throttling.

This reverts commit c4c0efb06f.

Fixes: c4c0efb06f ("cpufreq: qcom-cpufreq-hw: Add cpufreq qos for LMh")
Reported-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Bjorn Andersson 2023-03-23 15:33:43 -07:00 committed by Greg Kroah-Hartman
parent 2e8aad9cd5
commit 82f6ffb8e0
1 changed files with 0 additions and 14 deletions
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14
drivers/cpufreq/qcom-cpufreq-hw.c
View File

@ -13,7 +13,6 @@
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/pm_opp.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/units.h>
@ -57,8 +56,6 @@ struct qcom_cpufreq_data {
struct cpufreq_policy *policy;
bool per_core_dcvs;
struct freq_qos_request throttle_freq_req;
};
static unsigned long cpu_hw_rate, xo_rate;
@ -343,8 +340,6 @@ static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
throttled_freq = freq_hz / HZ_PER_KHZ;
freq_qos_update_request(&data->throttle_freq_req, throttled_freq);
/* Update thermal pressure (the boost frequencies are accepted) */
arch_update_thermal_pressure(policy->related_cpus, throttled_freq);
@ -437,14 +432,6 @@ static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index)
if (data->throttle_irq < 0)
return data->throttle_irq;
ret = freq_qos_add_request(&policy->constraints,
&data->throttle_freq_req, FREQ_QOS_MAX,
FREQ_QOS_MAX_DEFAULT_VALUE);
if (ret < 0) {
dev_err(&pdev->dev, "Failed to add freq constraint (%d)\n", ret);
return ret;
}
data->cancel_throttle = false;
data->policy = policy;
@ -511,7 +498,6 @@ static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
if (data->throttle_irq <= 0)
return;
freq_qos_remove_request(&data->throttle_freq_req);
free_irq(data->throttle_irq, data);
}