linux-kernel - Re: [PATCH v5 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver

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Date:   Tue, 17 Jul 2018 08:20:14 +0530
From:   Taniya Das <tdas@...eaurora.org>
To:     Evan Green <evgreen@...gle.com>
Cc:     rjw@...ysocki.net, viresh.kumar@...aro.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        sboyd@...nel.org, Rajendra Nayak <rnayak@...eaurora.org>,
        anischal@...eaurora.org, devicetree@...r.kernel.org,
        robh@...nel.org, Saravana Kannan <skannan@...eaurora.org>,
        amit.kucheria@...aro.org
Subject: Re: [PATCH v5 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW
 driver

Hello Evan,

Thank you for testing the patch.

On 7/17/2018 4:32 AM, Evan Green wrote:
> Hi Taniya,
> On Thu, Jul 12, 2018 at 11:06 AM Taniya Das <tdas@...eaurora.org> wrote:
>>
>> The CPUfreq HW present in some QCOM chipsets offloads the steps necessary
>> for changing the frequency of CPUs. The driver implements the cpufreq
>> driver interface for this hardware engine.
>>
>> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
>> Signed-off-by: Taniya Das <tdas@...eaurora.org>
>> ---
>>   drivers/cpufreq/Kconfig.arm       |  10 ++
>>   drivers/cpufreq/Makefile          |   1 +
>>   drivers/cpufreq/qcom-cpufreq-hw.c | 344 ++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 355 insertions(+)
>>   create mode 100644 drivers/cpufreq/qcom-cpufreq-hw.c
>>
> ...
>> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
>> new file mode 100644
>> index 0000000..fa25a95
>> --- /dev/null
>> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> ...
>> +static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>> +{
>> +       struct cpufreq_qcom *c;
>> +
>> +       c = qcom_freq_domain_map[policy->cpu];
>> +       if (!c) {
>> +               pr_err("No scaling support for CPU%d\n", policy->cpu);
>> +               return -ENODEV;
>> +       }
>> +
>> +       cpumask_copy(policy->cpus, &c->related_cpus);
>> +
>> +       policy->fast_switch_possible = true;
>> +       policy->freq_table = c->table;
>> +       policy->driver_data = c;
>> +
>> +       return 0;
> I haven't looked at this driver in detail, but I have tested it.
> Instead of the line above, I needed:
> 
> return cpufreq_table_validate_and_show(policy, c->table);
> 
> Without this the framework thinks that the min and max frequencies are
> zero, and then you get a warning about an invalid table. I also
> removed "policy->freq_table = c->table", since validate_and_show does
> this.
> -Evan
> 

The API is no longer supported,

https://patchwork.kernel.org/patch/10320897/

If you are using the 4.14 kernel, you do need to replace

-policy->freq_table = c->table;
+cpufreq_table_validate_and_show(policy, c->table);

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