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Message-ID: <4fb38a3b-ed26-6c02-e9de-59ce99ce563e@nvidia.com>
Date: Mon, 12 Oct 2020 22:36:25 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
CC: <rjw@...ysocki.net>, <sudeep.holla@....com>,
<thierry.reding@...il.com>, <jonathanh@...dia.com>,
<linux-pm@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <ksitaraman@...dia.com>,
<bbasu@...dia.com>, Sumit Gupta <sumitg@...dia.com>
Subject: Re: [PATCH v2 2/2] cpufreq: tegra194: Fix unlisted boot freq warning
>> Warning coming during boot because the boot freq set by bootloader
>> gets filtered out due to big freq steps while creating freq_table.
>> Fix this by setting closest higher frequency from freq_table.
>> Warning:
>> cpufreq: cpufreq_online: CPU0: Running at unlisted freq
>> cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed
>>
>> These warning messages also come during hotplug online of non-boot
>> CPU's while exiting from 'Suspend-to-RAM'. This happens because
>> during exit from 'Suspend-to-RAM', some time is taken to restore
>> last software requested CPU frequency written in register before
>> entering suspend.
>
> And who does this restoration ?
>
>> To fix this, adding online hook to wait till the
>> current frequency becomes equal or close to the last requested
>> frequency.
>>
>> Fixes: df320f89359c ("cpufreq: Add Tegra194 cpufreq driver")
>> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
>> ---
>> drivers/cpufreq/tegra194-cpufreq.c | 86 ++++++++++++++++++++++++++++++++++----
>> 1 file changed, 79 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
>> index d250e49..cc28b1e3 100644
>> --- a/drivers/cpufreq/tegra194-cpufreq.c
>> +++ b/drivers/cpufreq/tegra194-cpufreq.c
>> @@ -7,6 +7,7 @@
>> #include <linux/cpufreq.h>
>> #include <linux/delay.h>
>> #include <linux/dma-mapping.h>
>> +#include <linux/iopoll.h>
>> #include <linux/module.h>
>> #include <linux/of.h>
>> #include <linux/of_platform.h>
>> @@ -21,7 +22,6 @@
>> #define KHZ 1000
>> #define REF_CLK_MHZ 408 /* 408 MHz */
>> #define US_DELAY 500
>> -#define US_DELAY_MIN 2
>> #define CPUFREQ_TBL_STEP_HZ (50 * KHZ * KHZ)
>> #define MAX_CNT ~0U
>>
>> @@ -249,17 +249,22 @@ static unsigned int tegra194_get_speed(u32 cpu)
>> static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>> {
>> struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
>> - u32 cpu;
>> + u32 cpu = policy->cpu;
>> + int ret;
>> u32 cl;
>>
>> - smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);
>> + if (!cpu_online(cpu))
>
> Not required to check this.
>
OK.
>> + return -EINVAL;
>> +
>> + ret = smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
>> + if (ret) {
>
> Same as in the other patch.
>
Got.
>> + pr_err("cpufreq: Failed to get cluster for CPU%d\n", cpu);
>> + return ret;
>> + }
>>
>> if (cl >= data->num_clusters)
>> return -EINVAL;
>>
>> - /* boot freq */
>> - policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY_MIN);
>> -
>> /* set same policy for all cpus in a cluster */
>> for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
>> cpumask_set_cpu(cpu, policy->cpus);
>> @@ -267,7 +272,23 @@ static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
>> policy->freq_table = data->tables[cl];
>> policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
>>
>> - return 0;
>> + policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY);
>> +
>> + ret = cpufreq_table_validate_and_sort(policy);
>> + if (ret)
>> + return ret;
>> +
>> + /* Are we running at unknown frequency ? */
>> + ret = cpufreq_frequency_table_get_index(policy, policy->cur);
>> + if (ret == -EINVAL) {
>> + ret = __cpufreq_driver_target(policy, policy->cur - 1,
>> + CPUFREQ_RELATION_L);
>> + if (ret)
>> + return ret;
>
>> + policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY);
>
> cpufreq-core will do this anyway, you don't need to do it.
>
Got.
>> + }
>> +
>> + return ret;
>> }
>
> I wonder if I should change the pr_warn() in cpufreq-core to pr_info()
> instead, will that help you guys ? Will that still be a problem ? This
> is exactly same as what we do there.
>
Yes, this will also work. Then we don't need the current patch.
You want me to send a patch with change from pr_warn to pr_info?
>> static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
>> @@ -285,6 +306,55 @@ static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
>> return 0;
>> }
>>
>> +static int tegra194_cpufreq_online(struct cpufreq_policy *policy)
>> +{
>> + unsigned int interm_freq, last_set_freq;
>> + struct cpufreq_frequency_table *pos;
>> + u64 ndiv;
>> + int ret;
>> +
>> + if (!cpu_online(policy->cpu))
>> + return -EINVAL;
>> +
>> + /* get ndiv for the last frequency request from software */
>> + ret = smp_call_function_single(policy->cpu, get_cpu_ndiv, &ndiv, true);
>> + if (ret) {
>> + pr_err("cpufreq: Failed to get ndiv for CPU%d\n", policy->cpu);
>> + return ret;
>> + }
>> +
>> + cpufreq_for_each_valid_entry(pos, policy->freq_table) {
>> + if (pos->driver_data == ndiv) {
>> + last_set_freq = pos->frequency;
>> + break;
>> + }
>> + }
>> +
>> + policy->cur = tegra194_get_speed_common(policy->cpu, US_DELAY);
>> + interm_freq = policy->cur;
>> +
>> + /*
>> + * It takes some time to restore the previous frequency while
>> + * turning-on non-boot cores during exit from SC7(Suspend-to-RAM).
>> + * So, wait till it reaches the previous value and timeout if the
>> + * time taken to reach requested freq is >100ms
>> + */
>> + ret = read_poll_timeout(tegra194_get_speed_common, policy->cur,
>> + abs(policy->cur - last_set_freq) <= 115200, 0,
>> + 100 * USEC_PER_MSEC, false, policy->cpu,
>> + US_DELAY);
>
> The firmware does this update ? Why do we need to wait for this ? I
> was actually suggesting an empty tegra194_cpufreq_online() routine
> here.
> > --
> viresh
>
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