Re: [PATCH v14 4/4] PCI: qcom: Add OPP support to scale performance

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On 6/14/2024 6:12 PM, Ilpo Järvinen wrote:
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@xxxxxxxxxx>
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
  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 ?

Ack to all comments. I will update them in next patch series.

- Krishna chaitanya




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