Re: [PATCH v4 3/3] PCI: qcom-ep: Add ICC bandwidth voting support

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On 6/23/2023 11:04 AM, Manivannan Sadhasivam wrote:
On Wed, Jun 14, 2023 at 07:54:26PM +0530, Krishna chaitanya chundru wrote:
Add support to vote for ICC bandwidth based on the link
speed and width.

This patch is inspired from pcie-qcom driver to add basic
interconnect support.

Reference: commit c4860af88d0c ("PCI: qcom: Add basic interconnect
support").
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
  drivers/pci/controller/dwc/pcie-qcom-ep.c | 73 +++++++++++++++++++++++++++++++
  1 file changed, 73 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 19b3283..5d146ec 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
@@ -128,11 +130,19 @@
  /* DBI register fields */
  #define DBI_CON_STATUS_POWER_STATE_MASK		GENMASK(1, 0)
+#define DBI_LINKCTRLSTATUS 0x80
+#define DBI_LINKCTRLSTATUS_SHIFT		16
+
  #define XMLH_LINK_UP				0x400
  #define CORE_RESET_TIME_US_MIN			1000
  #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 +188,8 @@ struct qcom_pcie_ep {
  	struct phy *phy;
  	struct dentry *debugfs;
+ struct icc_path *icc_mem;
+
  	struct clk_bulk_data *clks;
  	int num_clks;
@@ -253,9 +265,51 @@ 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:
+		WARN_ON_ONCE(1);
We can drop WARN_ON_ONCE and print a warning saying that default GEN4 bandwidth
is being used.
done

+		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)
  {
  	int ret;
+	struct dw_pcie *pci = &pcie_ep->pci;
ret = clk_bulk_prepare_enable(pcie_ep->num_clks, pcie_ep->clks);
  	if (ret)
@@ -277,6 +331,20 @@ 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 average bandwidth corresponding to GEN1x1
Keep the comment same as the other driver.
done
+	 * for the pcie to 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_exit;
PHY should be powered off in the case of error.

Rest looks good.

- Mani

For platforms which need ICC it is must to vote for interconnect so better to power off in case of error.

-KC

+	}
+
  	return 0;
err_phy_exit:
@@ -550,6 +618,10 @@ 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;
  }
@@ -572,6 +644,7 @@ 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);
  	} else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
  		dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
  		val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
--
2.7.4




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