From 65fac3b3493f74eed6a7dcbc1835c1549b70f167 Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Wed, 4 May 2022 10:46:18 +0300 Subject: interconnect: qcom: icc-rpm: Fix for cached clock rate All nodes within an interconnect bus share interconnect bus clocks, but every node has its own cached clock rate values, this can lead to unexpected clock rate setting. Let's see an example shown in below, in this case, a bus have two nodes A and B, and its buswidth is 8: step1: vote bandwidth 1600M for node(A): aggregated(bw) = 1600M qcom_icc_node(A)->rate = 1600M / 8 = 200MHz step2: vote bandwidth 1600M for node(B): aggregated(bw) = 1600M + 1600M = 3200M qcom_icc_node(B)->rate = 3200M / 8 = 400MHz step3: unvote bandwidth 1600M for node(A) aggregated(bw) = 3200M - 1600M = 1600M target_clock = 1600M / 8 = 200MHz The problem is in step 3, the calculated target clock rate is 200MHz, which equals to the cached clock rate in node(A) (See step 1), unfortunately, qcom_icc_set() skips to set the new clock rate 200MHz in this case, so the bus clock rate will continue to stay at 400MHz. To resolve the issue, one possible solution is to invoke clk_get_rate() to retrieve the clock rates on the fly, thus we can totally remove the cached clock rates. But after review the code, many bus clock has set the flag CLK_GET_RATE_NOCACHE, this results in the retrieving bus clock rate is time cost for iterating parent clock nodes, and even challenges bus clock drivers to provide recalc_rate() callbacks. So this patch moves the cached rates into structure qcom_icc_provider, we use it as a central place to maintain bus clock handlers and cached clock rate, therefore, it can smoothly dismiss the mismatching problem. Signed-off-by: Leo Yan Link: https://lore.kernel.org/r/20220416031029.693211-2-leo.yan@linaro.org Signed-off-by: Georgi Djakov --- drivers/interconnect/qcom/icc-rpm.c | 4 ++-- drivers/interconnect/qcom/icc-rpm.h | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/interconnect') diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c index 34125e8f8b60..e0309e246523 100644 --- a/drivers/interconnect/qcom/icc-rpm.c +++ b/drivers/interconnect/qcom/icc-rpm.c @@ -274,7 +274,7 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst) do_div(rate, qn->buswidth); rate = min_t(u64, rate, LONG_MAX); - if (qn->rate == rate) + if (qp->bus_clk_rate == rate) return 0; for (i = 0; i < qp->num_clks; i++) { @@ -286,7 +286,7 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst) } } - qn->rate = rate; + qp->bus_clk_rate = rate; return 0; } diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h index 26dad006034f..4457fcc5b84c 100644 --- a/drivers/interconnect/qcom/icc-rpm.h +++ b/drivers/interconnect/qcom/icc-rpm.h @@ -26,6 +26,7 @@ enum qcom_icc_type { * @type: the ICC provider type * @qos_offset: offset to QoS registers * @regmap: regmap for QoS registers read/write access + * @bus_clk_rate: bus clock rate in Hz */ struct qcom_icc_provider { struct icc_provider provider; @@ -33,6 +34,7 @@ struct qcom_icc_provider { enum qcom_icc_type type; struct regmap *regmap; unsigned int qos_offset; + u64 bus_clk_rate; struct clk_bulk_data bus_clks[]; }; @@ -66,7 +68,6 @@ struct qcom_icc_qos { * @mas_rpm_id: RPM id for devices that are bus masters * @slv_rpm_id: RPM id for devices that are bus slaves * @qos: NoC QoS setting parameters - * @rate: current bus clock rate in Hz */ struct qcom_icc_node { unsigned char *name; @@ -77,7 +78,6 @@ struct qcom_icc_node { int mas_rpm_id; int slv_rpm_id; struct qcom_icc_qos qos; - u64 rate; }; struct qcom_icc_desc { -- cgit From 97f7d384ac4fcadfc0fb83519be23ccd59b4250b Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Wed, 4 May 2022 10:46:18 +0300 Subject: interconnect: qcom: icc-rpm: Cache every clock rate The cached clock rate is used for all bus clocks, thus it has the assumption that all interconnect clock rates are always same, this causes trouble if we want to set different clock rates separately. This patch is to allocate a clock rate array to cache every clock rate. Signed-off-by: Leo Yan Link: https://lore.kernel.org/r/20220416031029.693211-3-leo.yan@linaro.org Signed-off-by: Georgi Djakov --- drivers/interconnect/qcom/icc-rpm.c | 14 +++++++++----- drivers/interconnect/qcom/icc-rpm.h | 2 +- 2 files changed, 10 insertions(+), 6 deletions(-) (limited to 'drivers/interconnect') diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c index e0309e246523..45d23aaeabf6 100644 --- a/drivers/interconnect/qcom/icc-rpm.c +++ b/drivers/interconnect/qcom/icc-rpm.c @@ -274,20 +274,19 @@ static int qcom_icc_set(struct icc_node *src, struct icc_node *dst) do_div(rate, qn->buswidth); rate = min_t(u64, rate, LONG_MAX); - if (qp->bus_clk_rate == rate) - return 0; - for (i = 0; i < qp->num_clks; i++) { + if (qp->bus_clk_rate[i] == rate) + continue; + ret = clk_set_rate(qp->bus_clks[i].clk, rate); if (ret) { pr_err("%s clk_set_rate error: %d\n", qp->bus_clks[i].id, ret); return ret; } + qp->bus_clk_rate[i] = rate; } - qp->bus_clk_rate = rate; - return 0; } @@ -332,6 +331,11 @@ int qnoc_probe(struct platform_device *pdev) if (!qp) return -ENOMEM; + qp->bus_clk_rate = devm_kcalloc(dev, cd_num, sizeof(*qp->bus_clk_rate), + GFP_KERNEL); + if (!qp->bus_clk_rate) + return -ENOMEM; + data = devm_kzalloc(dev, struct_size(data, nodes, num_nodes), GFP_KERNEL); if (!data) diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h index 4457fcc5b84c..f6c4ac960102 100644 --- a/drivers/interconnect/qcom/icc-rpm.h +++ b/drivers/interconnect/qcom/icc-rpm.h @@ -34,7 +34,7 @@ struct qcom_icc_provider { enum qcom_icc_type type; struct regmap *regmap; unsigned int qos_offset; - u64 bus_clk_rate; + u64 *bus_clk_rate; struct clk_bulk_data bus_clks[]; }; -- cgit