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Message-ID: <04e7e509-9911-d5b2-619c-e7b87ed0ef50@linux.intel.com>
Date: Fri, 14 Jun 2024 15:42:20 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
cc: Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Bjorn Helgaas <bhelgaas@...gle.com>, johan+linaro@...nel.org,
bmasney@...hat.com, djakov@...nel.org,
Krzysztof Kozlowski <krzk+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
devicetree@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
linux-pci@...r.kernel.org, vireshk@...nel.org, quic_vbadigan@...cinc.com,
quic_skananth@...cinc.com, quic_nitegupt@...cinc.com,
quic_parass@...cinc.com, krzysztof.kozlowski@...aro.org
Subject: Re: [PATCH v14 4/4] PCI: qcom: Add OPP support to scale
performance
On Sun, 9 Jun 2024, Krishna chaitanya chundru wrote:
> QCOM Resource Power Manager-hardened (RPMh) is a hardware block which
> maintains hardware state of a regulator by performing max aggregation of
> the requests made by all of the clients.
>
> PCIe controller can operate on different RPMh performance state of power
> domain based on the speed of the link. And this performance state varies
> from target to target, like some controllers support GEN3 in NOM (Nominal)
> voltage corner, while some other supports GEN3 in low SVS (static voltage
> scaling).
>
> The SoC can be more power efficient if we scale the performance state
> based on the aggregate PCIe link bandwidth.
>
> Add Operating Performance Points (OPP) support to vote for RPMh state based
> on the aggregate link bandwidth.
>
> OPP can handle ICC bw voting also, so move ICC bw voting through OPP
> framework if OPP entries are present.
>
> As we are moving ICC voting as part of OPP, don't initialize ICC if OPP
> is supported.
>
> Before PCIe link is initialized vote for highest OPP in the OPP table,
> so that we are voting for maximum voltage corner for the link to come up
> in maximum supported speed.
>
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 93 +++++++++++++++++++++++++++-------
> 1 file changed, 75 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index ff1d891c8b9a..296e2d5036f6 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -21,6 +21,7 @@
> #include <linux/init.h>
> #include <linux/of.h>
> #include <linux/pci.h>
> +#include <linux/pm_opp.h>
> #include <linux/pm_runtime.h>
> #include <linux/platform_device.h>
> #include <linux/phy/pcie.h>
> @@ -1404,15 +1405,13 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
> return 0;
> }
>
> -static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
> +static void qcom_pcie_icc_opp_update(struct qcom_pcie *pcie)
> {
> + int speed, width, ret, freq_mbps;
> struct dw_pcie *pci = pcie->pci;
> + unsigned long freq_kbps;
> + struct dev_pm_opp *opp;
> u32 offset, status;
> - int speed, width;
> - int ret;
> -
> - if (!pcie->icc_mem)
> - return;
>
> offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
> @@ -1424,10 +1423,26 @@ static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
> speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
> width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
>
> - ret = icc_set_bw(pcie->icc_mem, 0, width * QCOM_PCIE_LINK_SPEED_TO_BW(speed));
> - if (ret) {
> - dev_err(pci->dev, "Failed to set bandwidth for PCIe-MEM interconnect path: %d\n",
> - ret);
> + if (pcie->icc_mem) {
> + ret = icc_set_bw(pcie->icc_mem, 0, width * QCOM_PCIE_LINK_SPEED_TO_BW(speed));
> + if (ret) {
> + dev_err(pci->dev, "Failed to set bandwidth for PCIe-MEM interconnect path: %d\n",
> + ret);
> + }
> + } else {
> + freq_mbps = pcie_link_speed_to_mbps(pcie_link_speed[speed]);
> + if (freq_mbps < 0)
> + return;
> +
> + freq_kbps = freq_mbps * 1000;
Use define from units.h instead of literal.
> + opp = dev_pm_opp_find_freq_exact(pci->dev, freq_kbps * width, true);
> + if (!IS_ERR(opp)) {
> + ret = dev_pm_opp_set_opp(pci->dev, opp);
> + if (ret)
> + dev_err(pci->dev, "Failed to set OPP for freq (%ld): %d\n",
> + freq_kbps * width, ret);
Make width unsigned and use %lu ?
--
i.
> + }
> + dev_pm_opp_put(opp);
> }
> }
>
> @@ -1471,7 +1486,9 @@ static void qcom_pcie_init_debugfs(struct qcom_pcie *pcie)
> static int qcom_pcie_probe(struct platform_device *pdev)
> {
> const struct qcom_pcie_cfg *pcie_cfg;
> + unsigned long max_freq = INT_MAX;
Why isn't this ULONG_MAX ?
You should also include <linux/limits.h>.
> struct device *dev = &pdev->dev;
> + struct dev_pm_opp *opp;
> struct qcom_pcie *pcie;
> struct dw_pcie_rp *pp;
> struct resource *res;
> @@ -1539,9 +1556,42 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> goto err_pm_runtime_put;
> }
>
> - ret = qcom_pcie_icc_init(pcie);
> - if (ret)
> + /* OPP table is optional */
> + ret = devm_pm_opp_of_add_table(dev);
> + if (ret && ret != -ENODEV) {
> + dev_err_probe(dev, ret, "Failed to add OPP table\n");
> goto err_pm_runtime_put;
> + }
> +
> + /*
> + * Before PCIe link is initialized vote for highest OPP in the OPP table,
> + * so that we are voting for maximum voltage corner for the link to come up
> + * in maximum supported speed. At the end of the probe(), OPP will be
> + * updated using qcom_pcie_icc_opp_update().
> + */
> + if (!ret) {
> + opp = dev_pm_opp_find_freq_floor(dev, &max_freq);
> + if (IS_ERR(opp)) {
> + dev_err_probe(pci->dev, PTR_ERR(opp),
> + "Unable to find max freq OPP\n");
> + goto err_pm_runtime_put;
> + } else {
> + ret = dev_pm_opp_set_opp(dev, opp);
> + }
> +
> + dev_pm_opp_put(opp);
> + if (ret) {
> + dev_err_probe(pci->dev, ret,
> + "Failed to set OPP for freq %ld\n",
> + max_freq);
It's unsigned so use %lu.
--
i.
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