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Date:   Thu, 13 Jul 2023 13:03:54 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Krishna chaitanya chundru <quic_krichai@quicinc.com>
Cc:     helgaas@kernel.org, linux-pci@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        quic_vbadigan@quicinc.com, quic_nitegupt@quicinc.com,
        quic_skananth@quicinc.com, quic_ramkri@quicinc.com,
        krzysztof.kozlowski@linaro.org,
        Manivannan Sadhasivam <mani@kernel.org>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Rob Herring <robh@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v7 3/3] PCI: qcom-ep: Add ICC bandwidth voting support
Message-ID: <20230713073354.GH3047@thinkpad>
References: <1688099123-28036-1-git-send-email-quic_krichai@quicinc.com>
 <1688099123-28036-4-git-send-email-quic_krichai@quicinc.com>
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On Fri, Jun 30, 2023 at 09:55:23AM +0530, Krishna chaitanya chundru wrote:
> Add support for voting interconnect (ICC) bandwidth based
> on the link speed and width.
> 
> This commit is inspired from the basic interconnect support added
> to pcie-qcom driver in commit c4860af88d0c ("PCI: qcom: Add basic
> interconnect support").
> 
> The interconnect support is kept optional to be backward compatible
> with legacy devicetrees.
> 
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
>  drivers/pci/controller/dwc/pcie-qcom-ep.c | 71 +++++++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 1435f51..cfe3061 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -13,6 +13,7 @@
>  #include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
> +#include <linux/interconnect.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/phy/pcie.h>
>  #include <linux/phy/phy.h>
> @@ -28,6 +29,7 @@
>  #define PARF_SYS_CTRL				0x00
>  #define PARF_DB_CTRL				0x10
>  #define PARF_PM_CTRL				0x20
> +#define PARF_PM_STTS				0x24
>  #define PARF_MHI_CLOCK_RESET_CTRL		0x174
>  #define PARF_MHI_BASE_ADDR_LOWER		0x178
>  #define PARF_MHI_BASE_ADDR_UPPER		0x17c
> @@ -133,6 +135,11 @@
>  #define CORE_RESET_TIME_US_MAX			1005
>  #define WAKE_DELAY_US				2000 /* 2 ms */
>  
> +#define PCIE_GEN1_BW_MBPS			250
> +#define PCIE_GEN2_BW_MBPS			500
> +#define PCIE_GEN3_BW_MBPS			985
> +#define PCIE_GEN4_BW_MBPS			1969
> +
>  #define to_pcie_ep(x)				dev_get_drvdata((x)->dev)
>  
>  enum qcom_pcie_ep_link_status {
> @@ -178,6 +185,8 @@ struct qcom_pcie_ep {
>  	struct phy *phy;
>  	struct dentry *debugfs;
>  
> +	struct icc_path *icc_mem;
> +
>  	struct clk_bulk_data *clks;
>  	int num_clks;
>  
> @@ -253,8 +262,49 @@ static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
>  	disable_irq(pcie_ep->perst_irq);
>  }
>  
> +static void qcom_pcie_ep_icc_update(struct qcom_pcie_ep *pcie_ep)
> +{
> +	struct dw_pcie *pci = &pcie_ep->pci;
> +	u32 offset, status, bw;
> +	int speed, width;
> +	int ret;
> +
> +	if (!pcie_ep->icc_mem)
> +		return;
> +
> +	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +	status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
> +
> +	speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
> +	width = FIELD_GET(PCI_EXP_LNKSTA_NLW, status);
> +
> +	switch (speed) {
> +	case 1:
> +		bw = MBps_to_icc(PCIE_GEN1_BW_MBPS);
> +		break;
> +	case 2:
> +		bw = MBps_to_icc(PCIE_GEN2_BW_MBPS);
> +		break;
> +	case 3:
> +		bw = MBps_to_icc(PCIE_GEN3_BW_MBPS);
> +		break;
> +	default:
> +		dev_warn(pci->dev, "using default GEN4 bandwidth\n");
> +		fallthrough;
> +	case 4:
> +		bw = MBps_to_icc(PCIE_GEN4_BW_MBPS);
> +		break;
> +	}
> +
> +	ret = icc_set_bw(pcie_ep->icc_mem, 0, width * bw);
> +	if (ret)
> +		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> +			ret);
> +}
> +
>  static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
>  {
> +	struct dw_pcie *pci = &pcie_ep->pci;
>  	int ret;
>  
>  	ret = clk_bulk_prepare_enable(pcie_ep->num_clks, pcie_ep->clks);
> @@ -277,8 +327,24 @@ static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
>  	if (ret)
>  		goto err_phy_exit;
>  
> +	/*
> +	 * Some Qualcomm platforms require interconnect bandwidth constraints
> +	 * to be set before enabling interconnect clocks.
> +	 *
> +	 * Set an initial peak bandwidth corresponding to single-lane Gen 1
> +	 * for the pcie-mem path.
> +	 */
> +	ret = icc_set_bw(pcie_ep->icc_mem, 0, MBps_to_icc(PCIE_GEN1_BW_MBPS));
> +	if (ret) {
> +		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> +			ret);
> +		goto err_phy_off;
> +	}
> +

You need to set bw to 0 during disable_resources() as well. Otherwise, it will
result in resource leakage when the driver is not in use.

- Mani

>  	return 0;
>  
> +err_phy_off:
> +	phy_power_off(pcie_ep->phy);
>  err_phy_exit:
>  	phy_exit(pcie_ep->phy);
>  err_disable_clk:
> @@ -550,6 +616,10 @@ static int qcom_pcie_ep_get_resources(struct platform_device *pdev,
>  	if (IS_ERR(pcie_ep->phy))
>  		ret = PTR_ERR(pcie_ep->phy);
>  
> +	pcie_ep->icc_mem = devm_of_icc_get(dev, "pcie-mem");
> +	if (IS_ERR(pcie_ep->icc_mem))
> +		ret = PTR_ERR(pcie_ep->icc_mem);
> +
>  	return ret;
>  }
>  
> @@ -573,6 +643,7 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
>  	} else if (FIELD_GET(PARF_INT_ALL_BME, status)) {
>  		dev_dbg(dev, "Received BME event. Link is enabled!\n");
>  		pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
> +		qcom_pcie_ep_icc_update(pcie_ep);
>  		pci_epc_bme_notify(pci->ep.epc);
>  	} else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
>  		dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
> -- 
> 2.7.4
> 

-- 
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