Re: [PATCH] powercap: add suspend and resume mechanism for SOC power limit

From: Rafael J. Wysocki
Date: Tue Jan 09 2018 - 06:40:42 EST


On Tuesday, January 9, 2018 9:25:10 AM CET xinx.sun@xxxxxxxxx wrote:
> From: Zhen Han <zhen.han@xxxxxxxxx>
>
> PL1 and PL2 could be throlled or de-throttled by
> Thermal management to control SOC temperature.
> However, currently, their value will be reset to default value
> after once system suspend and resume.
> Add pm_notifier to save PL1, PL2 before system suspect and restore
> PL1, PL2 after system resume.
>
> Signed-off-by: Sun Xinx <xinx.sun@xxxxxxxxx>

Jacob, Srinivas, please have a look at this.

> ---
> drivers/powercap/intel_rapl.c | 97 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 97 insertions(+)
>
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index d1694f1..0188cff 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -29,6 +29,7 @@
> #include <linux/sysfs.h>
> #include <linux/cpu.h>
> #include <linux/powercap.h>
> +#include <linux/suspend.h>
> #include <asm/iosf_mbi.h>
>
> #include <asm/processor.h>
> @@ -155,6 +156,7 @@ struct rapl_power_limit {
> int prim_id; /* primitive ID used to enable */
> struct rapl_domain *domain;
> const char *name;
> + u64 last_power_limit;
> };
>
> static const char pl1_name[] = "long_term";
> @@ -1533,6 +1535,92 @@ static int rapl_cpu_down_prep(unsigned int cpu)
>
> static enum cpuhp_state pcap_rapl_online;
>
> +static void power_limit_state_save(void)
> +{
> + struct rapl_package *rp;
> + struct rapl_domain *rd;
> + int nr_pl, ret, i;
> +
> + get_online_cpus();
> + list_for_each_entry(rp, &rapl_packages, plist) {
> + if (!rp->power_zone)
> + continue;
> + rd = power_zone_to_rapl_domain(rp->power_zone);
> + nr_pl = find_nr_power_limit(rd);
> + for (i = 0; i < nr_pl; i++) {
> + switch (rd->rpl[i].prim_id) {
> + case PL1_ENABLE:
> + ret = rapl_read_data_raw(rd,
> + POWER_LIMIT1,
> + true,
> + &rd->rpl[i].last_power_limit);
> + if (ret)
> + rd->rpl[i].last_power_limit = 0;
> + break;
> + case PL2_ENABLE:
> + ret = rapl_read_data_raw(rd,
> + POWER_LIMIT2,
> + true,
> + &rd->rpl[i].last_power_limit);
> + if (ret)
> + rd->rpl[i].last_power_limit = 0;
> + break;
> + }
> + }
> + }
> + put_online_cpus();
> +}
> +
> +static void power_limit_state_restore(void)
> +{
> + struct rapl_package *rp;
> + struct rapl_domain *rd;
> + int nr_pl, i;
> +
> + get_online_cpus();
> + list_for_each_entry(rp, &rapl_packages, plist) {
> + if (!rp->power_zone)
> + continue;
> + rd = power_zone_to_rapl_domain(rp->power_zone);
> + nr_pl = find_nr_power_limit(rd);
> + for (i = 0; i < nr_pl; i++) {
> + switch (rd->rpl[i].prim_id) {
> + case PL1_ENABLE:
> + if (rd->rpl[i].last_power_limit)
> + rapl_write_data_raw(rd,
> + POWER_LIMIT1,
> + rd->rpl[i].last_power_limit);
> + break;
> + case PL2_ENABLE:
> + if (rd->rpl[i].last_power_limit)
> + rapl_write_data_raw(rd,
> + POWER_LIMIT2,
> + rd->rpl[i].last_power_limit);
> + break;
> + }
> + }
> + }
> + put_online_cpus();
> +}
> +
> +static int rapl_pm_callback(struct notifier_block *nb,
> + unsigned long mode, void *_unused)
> +{
> + switch (mode) {
> + case PM_SUSPEND_PREPARE:
> + power_limit_state_save();
> + break;
> + case PM_POST_SUSPEND:
> + power_limit_state_restore();
> + break;
> + }
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block rapl_pm_notifier = {
> + .notifier_call = rapl_pm_callback,
> +};
> +
> static int __init rapl_init(void)
> {
> const struct x86_cpu_id *id;
> @@ -1560,8 +1648,16 @@ static int __init rapl_init(void)
>
> /* Don't bail out if PSys is not supported */
> rapl_register_psys();
> +
> + ret = register_pm_notifier(&rapl_pm_notifier);
> + if (ret)
> + goto err_unreg_all;
> +
> return 0;
>
> +err_unreg_all:
> + cpuhp_remove_state(pcap_rapl_online);
> +
> err_unreg:
> rapl_unregister_powercap();
> return ret;
> @@ -1569,6 +1665,7 @@ static int __init rapl_init(void)
>
> static void __exit rapl_exit(void)
> {
> + unregister_pm_notifier(&rapl_pm_notifier);
> cpuhp_remove_state(pcap_rapl_online);
> rapl_unregister_powercap();
> }
>