linux-kernel - Re: [PATCH v2 20/22] interconnect: qcom: icc-rpm: Set bandwidth on both contexts

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Message-ID: <ZIS6LK2lnlnNygX7@gerhold.net>
Date:   Sat, 10 Jun 2023 20:00:12 +0200
From:   Stephan Gerhold <stephan@...hold.net>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Georgi Djakov <djakov@...nel.org>,
        Leo Yan <leo.yan@...aro.org>,
        Evan Green <evgreen@...omium.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 20/22] interconnect: qcom: icc-rpm: Set bandwidth on
 both contexts

On Fri, Jun 09, 2023 at 10:19:25PM +0200, Konrad Dybcio wrote:
> Up until now, for some reason we've only been setting bandwidth values
> on the active-only context. That pretty much meant that RPM could lift
> all votes when entering sleep mode. Or never sleep at all.
> 
> That in turn could potentially break things like USB wakeup, as the
> connection between APSS and SNoC/PNoC would simply be dead.
> 

Nitpick: Apparently an "active" vote is applied during both active+sleep
until the first "sleep" vote is sent. It's documented only for
regulators [1] but I would expect the same applies to the bandwidths.
This means actual breakage shouldn't have been possible.

The patch itself is still the right thing to do to have the sleep state
correct during deep cpuidle/suspend.

[1]: https://git.codelinaro.org/clo/la/kernel/msm-3.10/-/blob/LA.BR.1.2.9.c26-04700-8x09.0/drivers/regulator/rpm-smd-regulator.c#L199-209

> Set the values appropriately.
> 
> Fixes: 30c8fa3ec61a ("interconnect: qcom: Add MSM8916 interconnect provider driver")
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>  drivers/interconnect/qcom/icc-rpm.c | 54 +++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index 3ac47b818afe..ac719013077e 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -205,34 +205,39 @@ static int qcom_icc_qos_set(struct icc_node *node)
>  	}
>  }
>  
> -static int qcom_icc_rpm_set(struct qcom_icc_node *qn, u64 sum_bw)
> +static int qcom_icc_rpm_set(struct qcom_icc_node *qn, u64 *bw)
>  {
> -	int ret = 0;
> +	int ret, rpm_ctx = 0;
> +	u64 bw_bps;
>  
>  	if (qn->qos.ap_owned)
>  		return 0;
>  
> -	if (qn->mas_rpm_id != -1) {
> -		ret = qcom_icc_rpm_smd_send(QCOM_SMD_RPM_ACTIVE_STATE,
> -					    RPM_BUS_MASTER_REQ,
> -					    qn->mas_rpm_id,
> -					    sum_bw);
> -		if (ret) {
> -			pr_err("qcom_icc_rpm_smd_send mas %d error %d\n",
> -			       qn->mas_rpm_id, ret);
> -			return ret;
> +	for (rpm_ctx = 0; rpm_ctx < QCOM_SMD_RPM_STATE_NUM; rpm_ctx++) {
> +		bw_bps = icc_units_to_bps(bw[rpm_ctx]);
> +
> +		if (qn->mas_rpm_id != -1) {
> +			ret = qcom_icc_rpm_smd_send(rpm_ctx,
> +						    RPM_BUS_MASTER_REQ,
> +						    qn->mas_rpm_id,
> +						    bw_bps);
> +			if (ret) {
> +				pr_err("qcom_icc_rpm_smd_send mas %d error %d\n",
> +				qn->mas_rpm_id, ret);
> +				return ret;
> +			}
>  		}
> -	}
>  
> -	if (qn->slv_rpm_id != -1) {
> -		ret = qcom_icc_rpm_smd_send(QCOM_SMD_RPM_ACTIVE_STATE,
> -					    RPM_BUS_SLAVE_REQ,
> -					    qn->slv_rpm_id,
> -					    sum_bw);
> -		if (ret) {
> -			pr_err("qcom_icc_rpm_smd_send slv %d error %d\n",
> -			       qn->slv_rpm_id, ret);
> -			return ret;
> +		if (qn->slv_rpm_id != -1) {
> +			ret = qcom_icc_rpm_smd_send(rpm_ctx,
> +						    RPM_BUS_SLAVE_REQ,
> +						    qn->slv_rpm_id,
> +						    bw_bps);
> +			if (ret) {
> +				pr_err("qcom_icc_rpm_smd_send slv %d error %d\n",
> +				qn->slv_rpm_id, ret);
> +				return ret;
> +			}
>  		}
>  	}
>  
> @@ -337,7 +342,6 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
>  	struct qcom_icc_provider *qp;
>  	struct qcom_icc_node *src_qn = NULL, *dst_qn = NULL;
>  	struct icc_provider *provider;
> -	u64 sum_bw;
>  	u64 active_rate, sleep_rate;
>  	u64 agg_avg[QCOM_SMD_RPM_STATE_NUM], agg_peak[QCOM_SMD_RPM_STATE_NUM];
>  	u64 max_agg_avg;
> @@ -351,14 +355,12 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
>  
>  	qcom_icc_bus_aggregate(provider, agg_avg, agg_peak, &max_agg_avg);
>  
> -	sum_bw = icc_units_to_bps(max_agg_avg);
> -
> -	ret = qcom_icc_rpm_set(src_qn, sum_bw);
> +	ret = qcom_icc_rpm_set(src_qn, agg_avg);
>  	if (ret)
>  		return ret;
>  
>  	if (dst_qn) {
> -		ret = qcom_icc_rpm_set(dst_qn, sum_bw);
> +		ret = qcom_icc_rpm_set(dst_qn, agg_avg);
>  		if (ret)
>  			return ret;
>  	}
> 
> -- 
> 2.41.0
>