linux-kernel - Re: [PATCH v2 03/10] interconnect: qcom: rpm: Always set QoS params on QNoC

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Date:   Tue, 10 Jan 2023 23:36:56 +0000
From:   Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org, krzysztof.kozlowski@...aro.org
Cc:     marijn.suijten@...ainline.org, Georgi Djakov <djakov@...nel.org>,
        AngeloGioacchino Del Regno <kholk11@...il.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 03/10] interconnect: qcom: rpm: Always set QoS params
 on QNoC

On 10/01/2023 13:21, Konrad Dybcio wrote:
> On newer SoCs, QoS parameters and RPM bandwidth requests are wholly
> separate. Setting one should only depend on the description of the
> interconnect node and not whether the other is present. If we don't
> vote through RPM, QoS parameters should be set regardless, as we're
> requesting additional bandwidth by setting the interconnect clock
> rates.
> 
> With NoC (the old-SoC bus type), this is not the case and they are
> mutually exclusive (so, the current upstream logic is correct).
> 
> For BIMC however, newer SoCs expect QoS params to be always set
> (like QNoC) whereas older ones (like MSM8998) hang up completely when
> doing so, hence this will be addressed in the next commit.
> 
> The Fixes tag references the commit in which this logic was added, it
> has since been shuffled around to a different file, but it's the one
> where it originates from.
> 
> Fixes: f80a1d414328 ("interconnect: qcom: Add SDM660 interconnect provider driver")
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/interconnect/qcom/icc-rpm.c | 20 ++++++++++++++++----
>   1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index cd1eab3d93ba..0516b74abdc7 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -246,15 +246,27 @@ static int qcom_icc_rpm_set(int mas_rpm_id, int slv_rpm_id, u64 sum_bw)
>   static int __qcom_icc_set(struct icc_node *n, struct qcom_icc_node *qn,
>   			  u64 sum_bw)
>   {
> +	struct qcom_icc_provider *qp = to_qcom_provider(n->provider);
> +	bool vote_ap, vote_rpm;
>   	int ret;
>   
> -	if (!qn->qos.ap_owned) {
> -		/* send bandwidth request message to the RPM processor */
> +	if (qp->type == QCOM_ICC_QNOC) {
> +		vote_ap = true;
> +		vote_rpm = true;
> +	} else {
> +		vote_ap = qn->qos.ap_owned;
> +		vote_rpm = !vote_ap;
> +	}
> +
> +	if (vote_rpm) {
> +		/* Send bandwidth request message to the RPM processor */
>   		ret = qcom_icc_rpm_set(qn->mas_rpm_id, qn->slv_rpm_id, sum_bw);
>   		if (ret)
>   			return ret;
> -	} else if (qn->qos.qos_mode != -1) {
> -		/* set bandwidth directly from the AP */
> +	}
> +
> +	if (vote_ap && qn->qos.qos_mode != NOC_QOS_MODE_INVALID) {
> +		/* Set QoS params from the AP */
>   		ret = qcom_icc_qos_set(n, sum_bw);
>   		if (ret)
>   			return ret;

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>