On Mon 07 Mar 07:30 PST 2022, Dmitry Baryshkov wrote:
> Provide lightweight online and offline operations. This saves us from
> parsing and tearing down the OPP tables each time the CPU is put online
> or offline.
Isn't that a slight understatement? Doesn't it also save us from e.g.
ioremapping the memory, traversing DT to discover the policy's
related_cpus and requesting the dcvs interrupt?
I like the idea of getting these things out of the init/exit path. I do
however think that we could move most of this to probe time, and thereby
be able to rely on devm operations for many of these things.
That said, I still like your idea of having a fast path for this...
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> drivers/cpufreq/qcom-cpufreq-hw.c | 28 ++++++++++++++++++++++++++--
> 1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 580520215ee7..12b67f16b78f 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -424,10 +424,26 @@ static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index)
> return 0;
> }
>
> -static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
> +static int qcom_cpufreq_hw_cpu_online(struct cpufreq_policy *policy)
> {
> + struct qcom_cpufreq_data *data = policy->driver_data;
> + struct platform_device *pdev = cpufreq_get_driver_data();
> + int ret;
> +
For backwards compatibility reasons it's valid to not have
data->throttle_irq. This will however cause irq_set_affinity_hint() to
return -EINVAL and we'll get a print.
So you should handle that gracefully.
> + ret = irq_set_affinity_hint(data->throttle_irq, policy->cpus);
> + if (ret)
> + dev_err(&pdev->dev, "Failed to set CPU affinity of %s[%d]\n",
> + data->irq_name, data->throttle_irq);
> +
> + return ret;
> +}
> +
> +static int qcom_cpufreq_hw_cpu_offline(struct cpufreq_policy *policy)
> +{
> + struct qcom_cpufreq_data *data = policy->driver_data;
> +
> if (data->throttle_irq <= 0)
> - return;
> + return 0;
>
> mutex_lock(&data->throttle_lock);
> data->cancel_throttle = true;
This will mark the throttle as cancelled, you need to clear this as
you're bringing the policy online again.
> @@ -435,6 +451,12 @@ static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
>
> cancel_delayed_work_sync(&data->throttle_work);
> irq_set_affinity_hint(data->throttle_irq, NULL);
You don't disable_irq(data->throttle_irq) here. I think
qcom_lmh_dcvs_notify() will be unhappy if we get thermal pressure from a
policy with no cpus?
Note though that you can't enable it in online(), as it will be enabled
in ready()...
> +
> + return 0;
> +}
> +
> +static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
> +{
> free_irq(data->throttle_irq, data);
As above, you should treat throttle_irq <= 0 gracefully.
Regards,
Bjorn
> }
>
> @@ -588,6 +610,8 @@ static struct cpufreq_driver cpufreq_qcom_hw_driver = {
> .get = qcom_cpufreq_hw_get,
> .init = qcom_cpufreq_hw_cpu_init,
> .exit = qcom_cpufreq_hw_cpu_exit,
> + .online = qcom_cpufreq_hw_cpu_online,
> + .offline = qcom_cpufreq_hw_cpu_offline,
> .register_em = cpufreq_register_em_with_opp,
> .fast_switch = qcom_cpufreq_hw_fast_switch,
> .name = "qcom-cpufreq-hw",
> --
> 2.34.1
>
