Re: [PATCH 2/3] firmware: arm_scmi: Populate fast channel rate_limit

From: Cristian Marussi
Date: Mon Mar 04 2024 - 03:00:32 EST

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On Thu, Feb 22, 2024 at 02:57:00PM +0100, Pierre Gondois wrote:
> Arm SCMI spec. v3.2, s4.5.3.12 PERFORMANCE_DESCRIBE_FASTCHANNEL
> defines a per-domain rate_limit for performance requests:
> """
> Rate Limit in microseconds, indicating the minimum time
> required between successive requests. A value of 0
> indicates that this field is not applicable or supported
> on the platform.
> """"
> The field is first defined in SCMI v2.0.
>
> Add support to fetch this value and advertise it through
> a fast_switch_rate_limit() callback.
>
> Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>

Hi,

LGTM.

Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>

Thanks,
Cristian

> ---
> drivers/firmware/arm_scmi/driver.c | 5 ++++-
> drivers/firmware/arm_scmi/perf.c | 32 +++++++++++++++++++++++----
> drivers/firmware/arm_scmi/powercap.c | 12 ++++++----
> drivers/firmware/arm_scmi/protocols.h | 4 +++-
> include/linux/scmi_protocol.h | 4 ++++
> 5 files changed, 47 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 3ea64b22cf0d..1d38ecfafc59 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -1617,7 +1617,7 @@ static void
> scmi_common_fastchannel_init(const struct scmi_protocol_handle *ph,
> u8 describe_id, u32 message_id, u32 valid_size,
> u32 domain, void __iomem **p_addr,
> - struct scmi_fc_db_info **p_db)
> + struct scmi_fc_db_info **p_db, u32 *rate_limit)
> {
> int ret;
> u32 flags;
> @@ -1661,6 +1661,9 @@ scmi_common_fastchannel_init(const struct scmi_protocol_handle *ph,
> goto err_xfer;
> }
>
> + if (rate_limit)
> + *rate_limit = le32_to_cpu(resp->rate_limit) & GENMASK(19, 0);
> +
> phys_addr = le32_to_cpu(resp->chan_addr_low);
> phys_addr |= (u64)le32_to_cpu(resp->chan_addr_high) << 32;
> addr = devm_ioremap(ph->dev, phys_addr, size);
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index 37c80376bd0a..fbcbd703198a 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -789,23 +789,27 @@ static void scmi_perf_domain_init_fc(const struct scmi_protocol_handle *ph,
>
> ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
> PERF_LEVEL_GET, 4, dom->id,
> - &fc[PERF_FC_LEVEL].get_addr, NULL);
> + &fc[PERF_FC_LEVEL].get_addr, NULL,
> + &fc[PERF_FC_LEVEL].rate_limit);
>
> ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
> PERF_LIMITS_GET, 8, dom->id,
> - &fc[PERF_FC_LIMIT].get_addr, NULL);
> + &fc[PERF_FC_LIMIT].get_addr, NULL,
> + &fc[PERF_FC_LIMIT].rate_limit);
>
> if (dom->info.set_perf)
> ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
> PERF_LEVEL_SET, 4, dom->id,
> &fc[PERF_FC_LEVEL].set_addr,
> - &fc[PERF_FC_LEVEL].set_db);
> + &fc[PERF_FC_LEVEL].set_db,
> + &fc[PERF_FC_LEVEL].rate_limit);
>
> if (dom->set_limits)
> ph->hops->fastchannel_init(ph, PERF_DESCRIBE_FASTCHANNEL,
> PERF_LIMITS_SET, 8, dom->id,
> &fc[PERF_FC_LIMIT].set_addr,
> - &fc[PERF_FC_LIMIT].set_db);
> + &fc[PERF_FC_LIMIT].set_db,
> + &fc[PERF_FC_LIMIT].rate_limit);
>
> dom->fc_info = fc;
> }
> @@ -974,6 +978,25 @@ static bool scmi_fast_switch_possible(const struct scmi_protocol_handle *ph,
> return dom->fc_info && dom->fc_info[PERF_FC_LEVEL].set_addr;
> }
>
> +static int scmi_fast_switch_rate_limit(const struct scmi_protocol_handle *ph,
> + u32 domain, u32 *rate_limit)
> +{
> + struct perf_dom_info *dom;
> +
> + if (!rate_limit)
> + return -EINVAL;
> +
> + dom = scmi_perf_domain_lookup(ph, domain);
> + if (IS_ERR(dom))
> + return PTR_ERR(dom);
> +
> + if (!dom->fc_info)
> + return -EINVAL;
> +
> + *rate_limit = dom->fc_info[PERF_FC_LEVEL].rate_limit;
> + return 0;
> +}
> +
> static enum scmi_power_scale
> scmi_power_scale_get(const struct scmi_protocol_handle *ph)
> {
> @@ -996,6 +1019,7 @@ static const struct scmi_perf_proto_ops perf_proto_ops = {
> .freq_get = scmi_dvfs_freq_get,
> .est_power_get = scmi_dvfs_est_power_get,
> .fast_switch_possible = scmi_fast_switch_possible,
> + .fast_switch_rate_limit = scmi_fast_switch_rate_limit,
> .power_scale_get = scmi_power_scale_get,
> };
>
> diff --git a/drivers/firmware/arm_scmi/powercap.c b/drivers/firmware/arm_scmi/powercap.c
> index a4c6cd4716fe..604184c044ff 100644
> --- a/drivers/firmware/arm_scmi/powercap.c
> +++ b/drivers/firmware/arm_scmi/powercap.c
> @@ -703,20 +703,24 @@ static void scmi_powercap_domain_init_fc(const struct scmi_protocol_handle *ph,
> ph->hops->fastchannel_init(ph, POWERCAP_DESCRIBE_FASTCHANNEL,
> POWERCAP_CAP_SET, 4, domain,
> &fc[POWERCAP_FC_CAP].set_addr,
> - &fc[POWERCAP_FC_CAP].set_db);
> + &fc[POWERCAP_FC_CAP].set_db,
> + &fc[POWERCAP_FC_CAP].rate_limit);
>
> ph->hops->fastchannel_init(ph, POWERCAP_DESCRIBE_FASTCHANNEL,
> POWERCAP_CAP_GET, 4, domain,
> - &fc[POWERCAP_FC_CAP].get_addr, NULL);
> + &fc[POWERCAP_FC_CAP].get_addr, NULL,
> + &fc[POWERCAP_FC_CAP].rate_limit);
>
> ph->hops->fastchannel_init(ph, POWERCAP_DESCRIBE_FASTCHANNEL,
> POWERCAP_PAI_SET, 4, domain,
> &fc[POWERCAP_FC_PAI].set_addr,
> - &fc[POWERCAP_FC_PAI].set_db);
> + &fc[POWERCAP_FC_PAI].set_db,
> + &fc[POWERCAP_FC_PAI].rate_limit);
>
> ph->hops->fastchannel_init(ph, POWERCAP_DESCRIBE_FASTCHANNEL,
> POWERCAP_PAI_GET, 4, domain,
> - &fc[POWERCAP_FC_PAI].get_addr, NULL);
> + &fc[POWERCAP_FC_PAI].get_addr, NULL,
> + &fc[POWERCAP_PAI_GET].rate_limit);
>
> *p_fc = fc;
> }
> diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h
> index e683c26f24eb..8b5d9ce4a33a 100644
> --- a/drivers/firmware/arm_scmi/protocols.h
> +++ b/drivers/firmware/arm_scmi/protocols.h
> @@ -234,6 +234,7 @@ struct scmi_fc_info {
> void __iomem *set_addr;
> void __iomem *get_addr;
> struct scmi_fc_db_info *set_db;
> + u32 rate_limit;
> };
>
> /**
> @@ -268,7 +269,8 @@ struct scmi_proto_helpers_ops {
> u8 describe_id, u32 message_id,
> u32 valid_size, u32 domain,
> void __iomem **p_addr,
> - struct scmi_fc_db_info **p_db);
> + struct scmi_fc_db_info **p_db,
> + u32 *rate_limit);
> void (*fastchannel_db_ring)(struct scmi_fc_db_info *db);
> };
>
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index acd956ffcb84..fafedb3b6604 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -139,6 +139,8 @@ struct scmi_perf_domain_info {
> * at a given frequency
> * @fast_switch_possible: indicates if fast DVFS switching is possible or not
> * for a given device
> + * @fast_switch_rate_limit: gets the minimum time (us) required between
> + * successive fast_switching requests
> * @power_scale_mw_get: indicates if the power values provided are in milliWatts
> * or in some other (abstract) scale
> */
> @@ -168,6 +170,8 @@ struct scmi_perf_proto_ops {
> unsigned long *rate, unsigned long *power);
> bool (*fast_switch_possible)(const struct scmi_protocol_handle *ph,
> u32 domain);
> + int (*fast_switch_rate_limit)(const struct scmi_protocol_handle *ph,
> + u32 domain, u32 *rate_limit);
> enum scmi_power_scale (*power_scale_get)(const struct scmi_protocol_handle *ph);
> };
>
> --
> 2.25.1
>

Next message: Alexandre Ghiti: "[PATCH] riscv: Fix compilation error with FAST_GUP and rv32"
Previous message: Mi, Dapeng: "Re: [PATCH] KVM: x86/svm/pmu: Set PerfMonV2 global control bits correctly"
Next in thread: Sudeep Holla: "Re: [PATCH 2/3] firmware: arm_scmi: Populate fast channel rate_limit"
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