Re: [Patch v3 3/6] cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support

Viresh Kumar
2021-07-09T06:46:52Z

On 08-07-21, 08:06, Thara Gopinath wrote:
> static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
> {
> struct platform_device *pdev = cpufreq_get_driver_data();
> @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
> dev_warn(cpu_dev, "failed to enable boost: %d\n", ret);
> }
>
> + ret = qcom_cpufreq_hw_lmh_init(policy, index);

You missed unregistering EM here (which is also missing from exit,
which you need to fix first in a separate patch).

> + if (ret)
> + goto error;
> +
> return 0;
> error:
> kfree(data);
> @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
>
> dev_pm_opp_remove_all_dynamic(cpu_dev);
> dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
> + if (data->lmh_dcvs_irq > 0) {
> + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data);

Why using devm variants here and while requesting the irq ?

> + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work);
> + }

Please move this to qcom_cpufreq_hw_lmh_exit() or something.

Now with sequence of disabling interrupt, etc, I see a potential
problem.

CPU0 CPU1

qcom_cpufreq_hw_cpu_exit()
-> devm_free_irq();
qcom_lmh_dcvs_poll()
-> qcom_lmh_dcvs_notify()
-> enable_irq()

-> cancel_delayed_work_sync();

What will happen if enable_irq() gets called after freeing the irq ?
Not sure, but it looks like you will hit this then from manage.c:

WARN(!desc->irq_data.chip, KERN_ERR "enable_irq before
setup/request_irq: irq %u\n", irq))

?

You got a chicken n egg problem :)

--
viresh