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[83.9.29.190]) by smtp.gmail.com with ESMTPSA id s20-20020a2e2c14000000b002b1a8b926f3sm949346ljs.3.2023.06.10.12.09.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 10 Jun 2023 12:09:20 -0700 (PDT) Message-ID: <5362844c-253c-b624-c8f0-81a06a891dbd@linaro.org> Date: Sat, 10 Jun 2023 21:09:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH v2 22/22] interconnect: qcom: icc-rpm: Fix bandwidth calculations Content-Language: en-US To: Stephan Gerhold Cc: Andy Gross , Bjorn Andersson , Michael Turquette , Stephen Boyd , Georgi Djakov , Leo Yan , Evan Green , Marijn Suijten , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-pm@vger.kernel.org References: <20230526-topic-smd_icc-v2-0-e5934b07d813@linaro.org> <20230526-topic-smd_icc-v2-22-e5934b07d813@linaro.org> From: Konrad Dybcio In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 10.06.2023 21:06, Stephan Gerhold wrote: > On Fri, Jun 09, 2023 at 10:19:27PM +0200, Konrad Dybcio wrote: >> Up until now, we've been aggregating the bandwidth values and only >> dividing them by the bus width of the source node. This was completely >> wrong, as different nodes on a given path may (and usually do) have >> varying bus widths. That in turn, resulted in the calculated clock rates >> being completely bogus - usually they ended up being much higher, as >> NoC_A<->NoC_B links are very wide. >> >> Since we're not using the aggregate bandwidth value for anything other >> than clock rate calculations, remodel qcom_icc_bus_aggregate() to >> calculate the per-context clock rate for a given provider, taking into >> account the bus width of every individual node. >> >> Fixes: 30c8fa3ec61a ("interconnect: qcom: Add MSM8916 interconnect provider driver") >> Reported-by: Stephan Gerhold >> Signed-off-by: Konrad Dybcio >> --- >> drivers/interconnect/qcom/icc-rpm.c | 59 ++++++++++++------------------------- >> 1 file changed, 19 insertions(+), 40 deletions(-) >> >> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c >> index 1508233632f6..d177a76abe2a 100644 >> --- a/drivers/interconnect/qcom/icc-rpm.c >> +++ b/drivers/interconnect/qcom/icc-rpm.c >> @@ -293,58 +293,44 @@ static int qcom_icc_bw_aggregate(struct icc_node *node, u32 tag, u32 avg_bw, >> } >> >> /** >> - * qcom_icc_bus_aggregate - aggregate bandwidth by traversing all nodes >> + * qcom_icc_bus_aggregate - calculate bus clock rates by traversing all nodes >> * @provider: generic interconnect provider >> - * @agg_avg: an array for aggregated average bandwidth of buckets >> - * @agg_peak: an array for aggregated peak bandwidth of buckets >> - * @max_agg_avg: pointer to max value of aggregated average bandwidth >> + * @agg_clk_rate: array containing the aggregated clock rates in kHz >> */ >> -static void qcom_icc_bus_aggregate(struct icc_provider *provider, >> - u64 *agg_avg, u64 *agg_peak, >> - u64 *max_agg_avg) >> +static void qcom_icc_bus_aggregate(struct icc_provider *provider, u64 *agg_clk_rate) >> { >> - struct icc_node *node; >> + u64 agg_avg_rate, agg_rate; >> struct qcom_icc_node *qn; >> - u64 sum_avg[QCOM_SMD_RPM_STATE_NUM]; >> + struct icc_node *node; >> int i; >> >> - /* Initialise aggregate values */ >> - for (i = 0; i < QCOM_SMD_RPM_STATE_NUM; i++) { >> - agg_avg[i] = 0; >> - agg_peak[i] = 0; >> - } >> - >> - *max_agg_avg = 0; >> - >> /* >> - * Iterate nodes on the interconnect and aggregate bandwidth >> - * requests for every bucket. >> + * Iterate nodes on the provider, aggregate bandwidth requests for >> + * every bucket and convert them into bus clock rates. >> */ >> list_for_each_entry(node, &provider->nodes, node_list) { >> qn = node->data; >> for (i = 0; i < QCOM_SMD_RPM_STATE_NUM; i++) { >> if (qn->channels) >> - sum_avg[i] = div_u64(qn->sum_avg[i], qn->channels); >> + agg_avg_rate = 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]); >> + agg_avg_rate = qn->sum_avg[i]; >> + >> + agg_rate = max_t(u64, agg_avg_rate, qn->max_peak[i]); >> + do_div(agg_rate, qn->buswidth); >> + >> + agg_clk_rate[i] = max_t(u64, agg_clk_rate[i], agg_rate); >> } >> } >> - >> - /* Find maximum values across all buckets */ >> - for (i = 0; i < QCOM_SMD_RPM_STATE_NUM; i++) >> - *max_agg_avg = max_t(u64, *max_agg_avg, agg_avg[i]); >> } >> >> 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; >> + u64 agg_clk_rate[QCOM_SMD_RPM_STATE_NUM] = { 0 }; >> struct icc_provider *provider; >> + struct qcom_icc_provider *qp; >> u64 active_rate, sleep_rate; >> - u64 agg_avg[QCOM_SMD_RPM_STATE_NUM], agg_peak[QCOM_SMD_RPM_STATE_NUM]; >> - u64 max_agg_avg; >> int ret; >> >> src_qn = src->data; >> @@ -353,7 +339,9 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst) >> provider = src->provider; >> qp = to_qcom_provider(provider); >> >> - qcom_icc_bus_aggregate(provider, agg_avg, agg_peak, &max_agg_avg); >> + qcom_icc_bus_aggregate(provider, agg_clk_rate); >> + active_rate = agg_clk_rate[QCOM_SMD_RPM_ACTIVE_STATE]; >> + sleep_rate = agg_clk_rate[QCOM_SMD_RPM_SLEEP_STATE]; >> >> ret = qcom_icc_rpm_set(src_qn, src_qn->sum_avg); >> if (ret) >> @@ -369,15 +357,6 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst) >> if (!qp->bus_clk_desc && !qp->bus_clk) >> return 0; >> >> - /* Intentionally keep the rates in kHz as that's what RPM accepts */ > > I kind of liked this comment because otherwise it's not obvious why > you're not converting from "ICC units" anywhere. I figured the kerneldoc change would be enough: @agg_clk_rate: array containing the aggregated clock rates in kHz > > Anyway: > > Reviewed-by: Stephan Gerhold > > Thanks for going through the giant maze to fix this! Thanks for being there along the way.. This spaghetti is far too much for a single human.. Konrad > > Stephan