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    SubjectRe: [PATCH v3 3/3] PCI: qcom: Add OPP support for speed based performance state of RPMH
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    On 8/22/2023 9:33 AM, Pavan Kondeti wrote:
    > On Mon, Aug 21, 2023 at 07:45:43PM +0530, Krishna chaitanya chundru wrote:
    >> Before link training vote for the maximum performance state of RPMH
    >> and once link is up, vote for the performance state based upon the link
    >> speed.
    >>
    >> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
    >> ---
    >> drivers/pci/controller/dwc/pcie-qcom.c | 47 ++++++++++++++++++++++++++++++++++
    >> 1 file changed, 47 insertions(+)
    >>
    >> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
    >> index 7a87a47..c57ca1a 100644
    >> --- a/drivers/pci/controller/dwc/pcie-qcom.c
    >> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
    >> @@ -22,6 +22,7 @@
    >> #include <linux/of_device.h>
    >> #include <linux/of_gpio.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>
    >> @@ -1357,6 +1358,32 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
    >> return 0;
    >> }
    >>
    >> +static void qcom_pcie_opp_update(struct qcom_pcie *pcie)
    >> +{
    >> + struct dw_pcie *pci = pcie->pci;
    >> + struct dev_pm_opp *opp;
    >> + u32 offset, status;
    >> + int speed, ret = 0;
    >> +
    >> + offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
    >> + status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
    >> +
    >> + /* Only update constraints if link is up. */
    >> + if (!(status & PCI_EXP_LNKSTA_DLLLA))
    >> + return;
    >> +
    > What happens if link is not up during probe? We set max vote before
    > this, should not we bring it down in suspend and vote it back again in
    > resume?

    ok, I will set to lower value in the suspend path if the link is not
    up.  If the link is already up driver will not

    do any modifications.

    >
    >> + speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
    >> +
    >> + opp = dev_pm_opp_find_level_exact(pci->dev, speed);
    >> + if (!IS_ERR(opp)) {
    >> + ret = dev_pm_opp_set_opp(pci->dev, opp);
    >> + if (ret)
    >> + dev_err(pci->dev, "Failed to set opp: %d\n", ret);
    >> + dev_pm_opp_put(opp);
    >> + }
    > Since you added an error message, make it more useful by printing the
    > opp level also. dev_pm_opp_get_level().
    Sure I will add this in next patch.
    >
    >> +
    >> +}
    >> +
    >> static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
    >> {
    >> struct dw_pcie *pci = pcie->pci;
    >> @@ -1439,8 +1466,10 @@ 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;
    >> struct device *dev = &pdev->dev;
    >> struct qcom_pcie *pcie;
    >> + struct dev_pm_opp *opp;
    >> struct dw_pcie_rp *pp;
    >> struct resource *res;
    >> struct dw_pcie *pci;
    >> @@ -1511,6 +1540,22 @@ static int qcom_pcie_probe(struct platform_device *pdev)
    >> if (ret)
    >> goto err_pm_runtime_put;
    >>
    >> + /* OPP table is optional */
    >> + ret = devm_pm_opp_of_add_table(dev);
    >> + if (ret && ret != -ENODEV) {
    >> + dev_err(dev, "Invalid OPP table in Device tree\n");
    >> + goto err_pm_runtime_put;
    >> + }
    >> +
    >> + /* vote for max level in the opp table */
    >> + opp = dev_pm_opp_find_freq_floor(dev, &max_freq);
    >> + if (!IS_ERR(opp)) {
    >> + ret = dev_pm_opp_set_opp(dev, opp);
    >> + if (ret)
    >> + dev_err(pci->dev, "Failed to set opp: %d\n", ret);
    >> + dev_pm_opp_put(opp);
    >> + }
    >> +
    > This needs an update since you moved from frequency based voting to link
    > speed based voting.

    dev_pm_opp_find_freq_floor will give us the max the opp level opp we
    don't have a similar API to get max opp-level

    For that reason we are using this API.

    - KC

    >
    >> ret = pcie->cfg->ops->get_resources(pcie);
    >> if (ret)
    >> goto err_pm_runtime_put;
    >> @@ -1531,6 +1576,8 @@ static int qcom_pcie_probe(struct platform_device *pdev)
    >>
    >> qcom_pcie_icc_update(pcie);
    >>
    >> + qcom_pcie_opp_update(pcie);
    >> +
    >> if (pcie->mhi)
    >> qcom_pcie_init_debugfs(pcie);
    >>
    >>
    > Thanks,
    > Pavan

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