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Message-ID: <20230713073354.GH3047@thinkpad>
Date: Thu, 13 Jul 2023 13:03:54 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
Cc: helgaas@...nel.org, linux-pci@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
quic_vbadigan@...cinc.com, quic_nitegupt@...cinc.com,
quic_skananth@...cinc.com, quic_ramkri@...cinc.com,
krzysztof.kozlowski@...aro.org,
Manivannan Sadhasivam <mani@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v7 3/3] PCI: qcom-ep: Add ICC bandwidth voting support
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@...cinc.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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