linux-kernel - Re: [PATCH 3/4] interconnect: qcom: icc-rpmh: Ensure floor BW is enforced for all nodes

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Date:   Fri, 02 Jul 2021 00:18:44 +0530
From:   okukatla@...eaurora.org
To:     Mike Tipton <mdtipton@...eaurora.org>
Cc:     djakov@...nel.org, bjorn.andersson@...aro.org, agross@...nel.org,
        saravanak@...gle.com, linux-arm-msm@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        mdtipton=codeaurora.org@...eaurora.org
Subject: Re: [PATCH 3/4] interconnect: qcom: icc-rpmh: Ensure floor BW is
 enforced for all nodes

On 2021-06-26 02:58, Mike Tipton wrote:
> We currently only enforce BW floors for a subset of nodes in a path.
> All BCMs that need updating are queued in the pre_aggregate/aggregate
> phase. The first set() commits all queued BCMs and subsequent set()
> calls short-circuit without committing anything. Since the floor BW
> isn't set in sum_avg/max_peak until set(), then some BCMs are committed
> before their associated nodes reflect the floor.
> 
> Set the floor as each node is being aggregated. This ensures that all
> all relevant floors are set before the BCMs are committed.
> 
> Fixes: 266cd33b5913 ("interconnect: qcom: Ensure that the floor
> bandwidth value is enforced")
> Signed-off-by: Mike Tipton <mdtipton@...eaurora.org>
> ---
>  drivers/interconnect/qcom/icc-rpmh.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpmh.c
> b/drivers/interconnect/qcom/icc-rpmh.c
> index bf01d09dba6c..f118f57eae37 100644
> --- a/drivers/interconnect/qcom/icc-rpmh.c
> +++ b/drivers/interconnect/qcom/icc-rpmh.c
> @@ -57,6 +57,11 @@ int qcom_icc_aggregate(struct icc_node *node, u32
> tag, u32 avg_bw,
>  			qn->sum_avg[i] += avg_bw;
>  			qn->max_peak[i] = max_t(u32, qn->max_peak[i], peak_bw);
>  		}
> +
> +		if (node->init_avg || node->init_peak) {
> +			qn->sum_avg[i] = max_t(u64, qn->sum_avg[i], node->init_avg);
> +			qn->max_peak[i] = max_t(u64, qn->max_peak[i], node->init_peak);
> +		}
Hi Mike,
Original problem is BCMs not getting added to commit_list for unused 
nodes, right? that is solved by moving *_bcm_voter_add() to 
pre_aggregate().
I could not get why we need to do above change, we are enforcing node 
votes with floor votes in framework + below code snippet that you 
removed.
How would adding this code in qcom_icc_aggregate() make difference? Is 
there any other issue that i am not to able to get?
>  	}
> 
>  	*agg_avg += avg_bw;
> @@ -90,11 +95,6 @@ int qcom_icc_set(struct icc_node *src, struct 
> icc_node *dst)
>  	qp = to_qcom_provider(node->provider);
>  	qn = node->data;
> 
> -	qn->sum_avg[QCOM_ICC_BUCKET_AMC] = max_t(u64,
> qn->sum_avg[QCOM_ICC_BUCKET_AMC],
> -						 node->avg_bw);
> -	qn->max_peak[QCOM_ICC_BUCKET_AMC] = max_t(u64,
> qn->max_peak[QCOM_ICC_BUCKET_AMC],
> -						  node->peak_bw);
> -
>  	qcom_icc_bcm_voter_commit(qp->voter);
> 
>  	return 0;