linux-kernel - Re: [PATCH v7 2/9] interconnect: qcom: rpm: Add support for specifying channel num

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Message-ID: <38fe0736-b566-9e1b-d7f3-71e3fcd01d90@linaro.org>
Date:   Tue, 21 Mar 2023 15:09:11 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Georgi Djakov <djakov@...nel.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/9] interconnect: qcom: rpm: Add support for
 specifying channel num



On 21.03.2023 15:06, Georgi Djakov wrote:
> Hi Konrad,
> 
> Thanks for the patch!
> 
> On 8.03.23 23:40, 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,
>> as we're supposed to feed msmbus with the per-channel bandwidth. Add
>> support for specifying that and use it during bandwidth aggregation.
>>
> 
> This looks good, but do you have any follow-up patch to use this and set
> the channels in some driver?
Yes, I have a couple of OOT drivers that are gonna make use of it.
TBF it should have been sent separately from the QoS mess, but I
don't think it's much of an issue to take it as-is.

The aforementioned OOT drivers for MSM8998 and SM6375 will be
submitted after we reach a consensus on how we want to ensure
that each node is guaranteed to have its clocks enabled before
access, among some other minor things.

Konrad
> 
> BR,
> Georgi
> 
>> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
>> 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 35fd75ae70e3..27c4c6497994 100644
>> --- a/drivers/interconnect/qcom/icc-rpm.c
>> +++ b/drivers/interconnect/qcom/icc-rpm.c
>> @@ -317,6 +317,7 @@ 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 */
>> @@ -334,7 +335,11 @@ 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)
>> +                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 8ba1918d7997..8aed5400afda 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];
>>
>