linux-kernel - Re: [PATCH 2/3] firmware: arm_scmi: Add perf_opp

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Date: Wed, 10 Jan 2024 12:59:06 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Sibi Sankar <quic_sibis@...cinc.com>
Cc: sudeep.holla@....com, cristian.marussi@....com, rafael@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, quic_mdtipton@...cinc.com,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/3] firmware: arm_scmi: Add perf_opp_xlate interface

On 08-01-24, 19:31, Sibi Sankar wrote:
> Add a new perf_opp_xlate interface to the existing perf_ops to translate
> a given perf index to frequency.
> 
> This can be used by the cpufreq driver and framework to determine the
> throttled frequency from a given perf index and apply HW pressure
> accordingly.
> 
> Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
> ---
>  drivers/firmware/arm_scmi/perf.c | 21 +++++++++++++++++++++
>  include/linux/scmi_protocol.h    |  3 +++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index c167bb5e3607..f26390924e1c 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -964,6 +964,26 @@ static int scmi_notify_support(const struct scmi_protocol_handle *ph, u32 domain
>  	return 0;
>  }
>  
> +static int scmi_perf_opp_xlate(const struct scmi_protocol_handle *ph, u32 domain,
> +			       int idx, unsigned long *freq)
> +{
> +	struct perf_dom_info *dom;
> +
> +	dom = scmi_perf_domain_lookup(ph, domain);
> +	if (IS_ERR(dom))
> +		return PTR_ERR(dom);
> +
> +	if (idx >= dom->opp_count)
> +		return -ERANGE;
> +
> +	if (!dom->level_indexing_mode)
> +		*freq = dom->opp[idx].perf * dom->mult_factor;
> +	else
> +		*freq = dom->opp[idx].indicative_freq * dom->mult_factor;
> +
> +	return 0;
> +}
> +
>  static const struct scmi_perf_proto_ops perf_proto_ops = {
>  	.num_domains_get = scmi_perf_num_domains_get,
>  	.info_get = scmi_perf_info_get,
> @@ -979,6 +999,7 @@ static const struct scmi_perf_proto_ops perf_proto_ops = {
>  	.fast_switch_possible = scmi_fast_switch_possible,
>  	.power_scale_get = scmi_power_scale_get,
>  	.perf_notify_support = scmi_notify_support,
> +	.perf_opp_xlate = scmi_perf_opp_xlate,

The use of "opp" here is a bit confusing as this doesn't have anything to do
with the OPP framework and you are only getting the frequency out of it after
all.

-- 
viresh