linux-kernel - Re: [PATCH v2 04/10] interconnect: qcom: rpm: Add support for specifying channel num

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Message-ID: <4a30931b-ef94-df2f-2e89-1028bf9510ce@linaro.org>
Date:   Tue, 10 Jan 2023 23:44:31 +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>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/10] interconnect: qcom: rpm: Add support for
 specifying channel num

On 10/01/2023 13:21, Konrad Dybcio wrote:
> Some nodes, like EBI0 (DDR) or L3/LLCC, may be connected over more than
> one channel. This should be taken into account in bandwidth calcualtion,
calculation

> as we're supposed to feed msmbus with the per-channel bandwidth. Add
> support for specifying that and use it during bandwidth aggregation.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/interconnect/qcom/icc-rpm.c | 7 ++++++-
>   drivers/interconnect/qcom/icc-rpm.h | 2 ++
>   2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index 0516b74abdc7..3207b4c99d04 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -336,6 +336,7 @@ static void qcom_icc_bus_aggregate(struct icc_provider *provider,
>   {
>   	struct icc_node *node;
>   	struct qcom_icc_node *qn;
> +	u64 sum_avg[QCOM_ICC_NUM_BUCKETS];
>   	int i;
>   
>   	/* Initialise aggregate values */
> @@ -353,7 +354,11 @@ static void qcom_icc_bus_aggregate(struct icc_provider *provider,
>   	list_for_each_entry(node, &provider->nodes, node_list) {
>   		qn = node->data;
>   		for (i = 0; i < QCOM_ICC_NUM_BUCKETS; i++) {
> -			agg_avg[i] += qn->sum_avg[i];
> +			if (qn->channels)

when do you actually populate channels ?

I had a quick scan of your series, I didn't see it..

> +				sum_avg[i] = div_u64(qn->sum_avg[i], qn->channels);
> +			else
> +				sum_avg[i] = qn->sum_avg[i];
> +			agg_avg[i] += sum_avg[i];
>   			agg_peak[i] = max_t(u64, agg_peak[i], qn->max_peak[i]);
>   		}
>   	}
> diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h
> index 3762648f9d47..eb51680f890d 100644
> --- a/drivers/interconnect/qcom/icc-rpm.h
> +++ b/drivers/interconnect/qcom/icc-rpm.h
> @@ -66,6 +66,7 @@ struct qcom_icc_qos {
>    * @id: a unique node identifier
>    * @links: an array of nodes where we can go next while traversing
>    * @num_links: the total number of @links
> + * @channels: number of channels at this node (e.g. DDR channels)
>    * @buswidth: width of the interconnect between a node and the bus (bytes)
>    * @sum_avg: current sum aggregate value of all avg bw requests
>    * @max_peak: current max aggregate value of all peak bw requests
> @@ -78,6 +79,7 @@ struct qcom_icc_node {
>   	u16 id;
>   	const u16 *links;
>   	u16 num_links;
> +	u16 channels;
>   	u16 buswidth;
>   	u64 sum_avg[QCOM_ICC_NUM_BUCKETS];
>   	u64 max_peak[QCOM_ICC_NUM_BUCKETS];