Re: [PATCH v2] powercap: Add Power Limit4 support

Rafael J. Wysocki
2020-07-14T13:21:30Z

On Tue, Jul 14, 2020 at 10:22 AM Sumeet Pawnikar
<sumeet.r.pawnikar@intel.com> wrote:
>
> Modern Intel Mobile platforms support power limit4 (PL4), which is
> the SoC package level maximum power limit (in Watts). It can be used
> to preemptively limits potential SoC power to prevent power spikes
> from tripping the power adapter and battery over-current protection.
> This patch enables this feature by exposing package level peak power
> capping control to userspace via RAPL sysfs interface. With this,
> application like DTPF can modify PL4 power limit, the similar way
> of other package power limit (PL1).
> As this feature is not tested on previous generations, here it is
> enabled only for the platform that has been verified to work,
> for safety concerns.

Thanks for the better changelog!

> Signed-off-by: Sumeet Pawnikar <sumeet.r.pawnikar@intel.com>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>

But why is the Rui's S-o-b under your patch?

Is it there because Rui has contributed to the patch? If so, you
should have used the Co-developed-by tag instead.

Srinivas, does the patch look good to you?

> ---
> Changes in v2:
> - Addressed review comments from Rafael.
> - Made the commit message more clearer.
> - Updated powercap documentation.
> ---
> Documentation/power/powercap/powercap.rst | 14 +++++---
> drivers/powercap/intel_rapl_common.c | 54 +++++++++++++++++++++++++++--
> drivers/powercap/intel_rapl_msr.c | 15 ++++++++
> include/linux/intel_rapl.h | 5 ++-
> 4 files changed, 80 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/power/powercap/powercap.rst b/Documentation/power/powercap/powercap.rst
> index 7ae3b44c7624..b3af059b6d5d 100644
> --- a/Documentation/power/powercap/powercap.rst
> +++ b/Documentation/power/powercap/powercap.rst
> @@ -167,11 +167,12 @@ For example::
> package-0
> ---------
>
> -The Intel RAPL technology allows two constraints, short term and long term,
> -with two different time windows to be applied to each power zone. Thus for
> -each zone there are 2 attributes representing the constraint names, 2 power
> -limits and 2 attributes representing the sizes of the time windows. Such that,
> -constraint_j_* attributes correspond to the jth constraint (j = 0,1).
> +Depending on different power zones, the Intel RAPL technology allows
> +one or multiple constraints like short term, long term and peak power,
> +with different time windows to be applied to each power zone.
> +All the zones contain attributes representing the constraint names,
> +power limits and the sizes of the time windows. Such that,
> +constraint_j_* attributes correspond to the jth constraint (j = 0,1,2).
>
> For example::
>
> @@ -181,6 +182,9 @@ For example::
> constraint_1_name
> constraint_1_power_limit_uw
> constraint_1_time_window_us
> + constraint_2_name
> + constraint_2_power_limit_uw
> + constraint_2_time_window_us
>
> Power Zone Attributes
> =====================
> diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c
> index 61a63a16b5e7..a8bcc58d61f0 100644
> --- a/drivers/powercap/intel_rapl_common.c
> +++ b/drivers/powercap/intel_rapl_common.c
> @@ -39,6 +39,8 @@
> #define POWER_HIGH_LOCK BIT_ULL(63)
> #define POWER_LOW_LOCK BIT(31)
>
> +#define POWER_LIMIT4_MASK 0x1FFF
> +
> #define TIME_WINDOW1_MASK (0x7FULL<<17)
> #define TIME_WINDOW2_MASK (0x7FULL<<49)
>
> @@ -82,6 +84,7 @@ enum unit_type {
>
> static const char pl1_name[] = "long_term";
> static const char pl2_name[] = "short_term";
> +static const char pl4_name[] = "peak_power";
>
> #define power_zone_to_rapl_domain(_zone) \
> container_of(_zone, struct rapl_domain, power_zone)
> @@ -337,6 +340,9 @@ static int set_power_limit(struct powercap_zone *power_zone, int cid,
> case PL2_ENABLE:
> rapl_write_data_raw(rd, POWER_LIMIT2, power_limit);
> break;
> + case PL4_ENABLE:
> + rapl_write_data_raw(rd, POWER_LIMIT4, power_limit);
> + break;
> default:
> ret = -EINVAL;
> }
> @@ -371,6 +377,9 @@ static int get_current_power_limit(struct powercap_zone *power_zone, int cid,
> case PL2_ENABLE:
> prim = POWER_LIMIT2;
> break;
> + case PL4_ENABLE:
> + prim = POWER_LIMIT4;
> + break;
> default:
> put_online_cpus();
> return -EINVAL;
> @@ -440,6 +449,13 @@ static int get_time_window(struct powercap_zone *power_zone, int cid,
> case PL2_ENABLE:
> ret = rapl_read_data_raw(rd, TIME_WINDOW2, true, &val);
> break;
> + case PL4_ENABLE:
> + /*
> + * Time window parameter is not applicable for PL4 entry
> + * so assigining '0' as default value.
> + */
> + val = 0;
> + break;
> default:
> put_online_cpus();
> return -EINVAL;
> @@ -483,6 +499,9 @@ static int get_max_power(struct powercap_zone *power_zone, int id, u64 *data)
> case PL2_ENABLE:
> prim = MAX_POWER;
> break;
> + case PL4_ENABLE:
> + prim = MAX_POWER;
> + break;
> default:
> put_online_cpus();
> return -EINVAL;
> @@ -492,6 +511,10 @@ static int get_max_power(struct powercap_zone *power_zone, int id, u64 *data)
> else
> *data = val;
>
> + /* As a generalization rule, PL4 would be around two times PL2. */
> + if (rd->rpl[id].prim_id == PL4_ENABLE)
> + *data = *data * 2;
> +
> put_online_cpus();
>
> return ret;
> @@ -524,12 +547,22 @@ static void rapl_init_domains(struct rapl_package *rp)
> rd->id = i;
> rd->rpl[0].prim_id = PL1_ENABLE;
> rd->rpl[0].name = pl1_name;
> - /* some domain may support two power limits */
> - if (rp->priv->limits[i] == 2) {
> +
> + /*
> + * The PL2 power domain is applicable for limits two
> + * and limits three
> + */
> + if (rp->priv->limits[i] >= 2) {
> rd->rpl[1].prim_id = PL2_ENABLE;
> rd->rpl[1].name = pl2_name;
> }
>
> + /* Enable PL4 domain if the total power limits are three */
> + if (rp->priv->limits[i] == 3) {
> + rd->rpl[2].prim_id = PL4_ENABLE;
> + rd->rpl[2].name = pl4_name;
> + }
> +
> for (j = 0; j < RAPL_DOMAIN_REG_MAX; j++)
> rd->regs[j] = rp->priv->regs[i][j];
>
> @@ -587,6 +620,8 @@ static u64 rapl_unit_xlate(struct rapl_domain *rd, enum unit_type type,
> RAPL_DOMAIN_REG_LIMIT, POWER_UNIT, 0),
> PRIMITIVE_INFO_INIT(POWER_LIMIT2, POWER_LIMIT2_MASK, 32,
> RAPL_DOMAIN_REG_LIMIT, POWER_UNIT, 0),
> + PRIMITIVE_INFO_INIT(POWER_LIMIT4, POWER_LIMIT4_MASK, 0,
> + RAPL_DOMAIN_REG_PL4, POWER_UNIT, 0),
> PRIMITIVE_INFO_INIT(FW_LOCK, POWER_LOW_LOCK, 31,
> RAPL_DOMAIN_REG_LIMIT, ARBITRARY_UNIT, 0),
> PRIMITIVE_INFO_INIT(PL1_ENABLE, POWER_LIMIT1_ENABLE, 15,
> @@ -597,6 +632,8 @@ static u64 rapl_unit_xlate(struct rapl_domain *rd, enum unit_type type,
> RAPL_DOMAIN_REG_LIMIT, ARBITRARY_UNIT, 0),
> PRIMITIVE_INFO_INIT(PL2_CLAMP, POWER_LIMIT2_CLAMP, 48,
> RAPL_DOMAIN_REG_LIMIT, ARBITRARY_UNIT, 0),
> + PRIMITIVE_INFO_INIT(PL4_ENABLE, POWER_LIMIT4_MASK, 0,
> + RAPL_DOMAIN_REG_PL4, ARBITRARY_UNIT, 0),
> PRIMITIVE_INFO_INIT(TIME_WINDOW1, TIME_WINDOW1_MASK, 17,
> RAPL_DOMAIN_REG_LIMIT, TIME_UNIT, 0),
> PRIMITIVE_INFO_INIT(TIME_WINDOW2, TIME_WINDOW2_MASK, 49,
> @@ -1252,6 +1289,7 @@ void rapl_remove_package(struct rapl_package *rp)
> if (find_nr_power_limit(rd) > 1) {
> rapl_write_data_raw(rd, PL2_ENABLE, 0);
> rapl_write_data_raw(rd, PL2_CLAMP, 0);
> + rapl_write_data_raw(rd, PL4_ENABLE, 0);
> }
> if (rd->id == RAPL_DOMAIN_PACKAGE) {
> rd_package = rd;
> @@ -1360,6 +1398,13 @@ static void power_limit_state_save(void)
> if (ret)
> rd->rpl[i].last_power_limit = 0;
> break;
> + case PL4_ENABLE:
> + ret = rapl_read_data_raw(rd,
> + POWER_LIMIT4, true,
> + &rd->rpl[i].last_power_limit);
> + if (ret)
> + rd->rpl[i].last_power_limit = 0;
> + break;
> }
> }
> }
> @@ -1390,6 +1435,11 @@ static void power_limit_state_restore(void)
> rapl_write_data_raw(rd, POWER_LIMIT2,
> rd->rpl[i].last_power_limit);
> break;
> + case PL4_ENABLE:
> + if (rd->rpl[i].last_power_limit)
> + rapl_write_data_raw(rd, POWER_LIMIT4,
> + rd->rpl[i].last_power_limit);
> + break;
> }
> }
> }
> diff --git a/drivers/powercap/intel_rapl_msr.c b/drivers/powercap/intel_rapl_msr.c
> index d5487965bdfe..83c76454623e 100644
> --- a/drivers/powercap/intel_rapl_msr.c
> +++ b/drivers/powercap/intel_rapl_msr.c
> @@ -28,6 +28,7 @@
>
> /* Local defines */
> #define MSR_PLATFORM_POWER_LIMIT 0x0000065C
> +#define MSR_VR_CURRENT_CONFIG 0x00000601
>
> /* private data for RAPL MSR Interface */
> static struct rapl_if_priv rapl_msr_priv = {
> @@ -123,13 +124,27 @@ static int rapl_msr_write_raw(int cpu, struct reg_action *ra)
> return ra->err;
> }
>
> +/* List of verified CPUs. */
> +static const struct x86_cpu_id pl4_support_ids[] = {
> + { X86_VENDOR_INTEL, 6, INTEL_FAM6_TIGERLAKE_L, X86_FEATURE_ANY },
> + {}
> +};
> +
> static int rapl_msr_probe(struct platform_device *pdev)
> {
> int ret;
> + const struct x86_cpu_id *id = x86_match_cpu(pl4_support_ids);
>
> rapl_msr_priv.read_raw = rapl_msr_read_raw;
> rapl_msr_priv.write_raw = rapl_msr_write_raw;
>
> + if (id) {
> + rapl_msr_priv.limits[RAPL_DOMAIN_PACKAGE] = 3;
> + rapl_msr_priv.regs[RAPL_DOMAIN_PACKAGE][RAPL_DOMAIN_REG_PL4] =
> + MSR_VR_CURRENT_CONFIG;
> + pr_info("PL4 support detected.\n");
> + }
> +
> rapl_msr_priv.control_type = powercap_register_control_type(NULL, "intel-rapl", NULL);
> if (IS_ERR(rapl_msr_priv.control_type)) {
> pr_debug("failed to register powercap control_type.\n");
> diff --git a/include/linux/intel_rapl.h b/include/linux/intel_rapl.h
> index efb3ce892c20..3582176a1eca 100644
> --- a/include/linux/intel_rapl.h
> +++ b/include/linux/intel_rapl.h
> @@ -29,6 +29,7 @@ enum rapl_domain_reg_id {
> RAPL_DOMAIN_REG_PERF,
> RAPL_DOMAIN_REG_POLICY,
> RAPL_DOMAIN_REG_INFO,
> + RAPL_DOMAIN_REG_PL4,
> RAPL_DOMAIN_REG_MAX,
> };
>
> @@ -38,12 +39,14 @@ enum rapl_primitives {
> ENERGY_COUNTER,
> POWER_LIMIT1,
> POWER_LIMIT2,
> + POWER_LIMIT4,
> FW_LOCK,
>
> PL1_ENABLE, /* power limit 1, aka long term */
> PL1_CLAMP, /* allow frequency to go below OS request */
> PL2_ENABLE, /* power limit 2, aka short term, instantaneous */
> PL2_CLAMP,
> + PL4_ENABLE, /* power limit 4, aka max peak power */
>
> TIME_WINDOW1, /* long term */
> TIME_WINDOW2, /* short term */
> @@ -65,7 +68,7 @@ struct rapl_domain_data {
> unsigned long timestamp;
> };
>
> -#define NR_POWER_LIMITS (2)
> +#define NR_POWER_LIMITS (3)
> struct rapl_power_limit {
> struct powercap_zone_constraint *constraint;
> int prim_id; /* primitive ID used to enable */
> --
> 1.7.9.5
>