Re: [PATCH v5 1/3] PCI: qcom: Add system PM support

Rob Herring
2022-08-10T21:50:27Z

On Wed, Aug 03, 2022 at 04:58:52PM +0530, Krishna chaitanya chundru wrote:
> Add suspend and resume pm callbacks.
>
> When system suspends, and if the link is in L1ss, disable the clocks
> and power down the phy so that system enters into low power state to
> save the maximum power. And when the system resumes, enable the clocks
> back and power on phy if they are disabled in the suspend path.
>
> we are doing this only when link is in l1ss but not in L2/L3 as
> no where we are forcing link to L2/L3 by sending PME turn off.
>
> is_suspended flag indicates if the clocks are disabled in the suspend
> path or not. And this flag is being used to restrict the access to
> config space, dbi etc when clock are turned-off.
>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
> Changes since v4:
> - Rebasing the code and removed the supports_system_suspend flag
> - in the resume path as is_suspended will serve its purpose.
> Changes since v3:
> - Powering down the phy in suspend and powering it on resume to
> acheive maximum power savings.
> Changes since v2:
> - Replaced the enable, disable clks ops with suspend and resume
> - Renamed support_pm_opsi flag with supports_system_suspend.
> Changes since v1:
> - Fixed compilation errors.
> ---
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 76 ++++++++++++++++++++++++++++++++++
> 1 file changed, 76 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index ccf6953..9dd50fc0 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -44,6 +44,9 @@
> #define PCIE20_PARF_PM_CTRL 0x20
> #define REQ_NOT_ENTR_L1 BIT(5)
>
> +#define PCIE20_PARF_PM_STTS 0x24
> +#define PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB BIT(8)
> +
> #define PCIE20_PARF_PHY_CTRL 0x40
> #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK GENMASK(20, 16)
> #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x) ((x) << 16)
> @@ -211,6 +214,8 @@ struct qcom_pcie_ops {
> void (*post_deinit)(struct qcom_pcie *pcie);
> void (*ltssm_enable)(struct qcom_pcie *pcie);
> int (*config_sid)(struct qcom_pcie *pcie);
> + int (*suspend)(struct qcom_pcie *pcie);
> + int (*resume)(struct qcom_pcie *pcie);

This is really the wrong direction. We don't need the DWC driver
defining per platform ops and then a platform defining sub-platform ops.
IOW, qcom_pcie_ops should go away.

But for now, you don't even need the ops as only 1 version is
implemented. Do you really expect other versions to do something
different than turn off clocks and phys?

> };
>
> struct qcom_pcie_cfg {
> @@ -219,6 +224,7 @@ struct qcom_pcie_cfg {
> unsigned int has_ddrss_sf_tbu_clk:1;
> unsigned int has_aggre0_clk:1;
> unsigned int has_aggre1_clk:1;
> + unsigned int supports_system_suspend:1;
> };
>
> struct qcom_pcie {
> @@ -229,6 +235,7 @@ struct qcom_pcie {
> struct phy *phy;
> struct gpio_desc *reset;
> const struct qcom_pcie_cfg *cfg;
> + unsigned int is_suspended:1;
> };
>
> #define to_qcom_pcie(x) dev_get_drvdata((x)->dev)
> @@ -1297,6 +1304,29 @@ static void qcom_pcie_deinit_2_7_0(struct qcom_pcie *pcie)
> regulator_bulk_disable(ARRAY_SIZE(res->supplies), res->supplies);
> }
>
> +static int qcom_pcie_resume_2_7_0(struct qcom_pcie *pcie)
> +{
> + struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> + int ret;
> +
> + ret = clk_bulk_prepare_enable(res->num_clks, res->clks);
> +
> + phy_power_on(pcie->phy);
> +
> + return ret;
> +}
> +
> +static int qcom_pcie_suspend_2_7_0(struct qcom_pcie *pcie)
> +{
> + struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> +
> + phy_power_off(pcie->phy);
> +
> + clk_bulk_disable_unprepare(res->num_clks, res->clks);
> +
> + return 0;
> +}
> +
> static int qcom_pcie_get_resources_2_9_0(struct qcom_pcie *pcie)
> {
> struct qcom_pcie_resources_2_9_0 *res = &pcie->res.v2_9_0;
> @@ -1590,6 +1620,8 @@ static const struct qcom_pcie_ops ops_1_9_0 = {
> .deinit = qcom_pcie_deinit_2_7_0,
> .ltssm_enable = qcom_pcie_2_3_2_ltssm_enable,
> .config_sid = qcom_pcie_config_sid_sm8250,
> + .suspend = qcom_pcie_suspend_2_7_0,
> + .resume = qcom_pcie_resume_2_7_0,
> };
>
> /* Qcom IP rev.: 2.9.0 Synopsys IP rev.: 5.00a */
> @@ -1655,6 +1687,7 @@ static const struct qcom_pcie_cfg sm8450_pcie1_cfg = {
> static const struct qcom_pcie_cfg sc7280_cfg = {
> .ops = &ops_1_9_0,
> .has_tbu_clk = true,
> + .supports_system_suspend = true,
> };
>
> static const struct qcom_pcie_cfg sc8180x_cfg = {
> @@ -1760,6 +1793,48 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> return ret;
> }
>
> +static int __maybe_unused qcom_pcie_pm_suspend(struct device *dev)
> +{
> + struct qcom_pcie *pcie = dev_get_drvdata(dev);
> + u32 val;
> +
> + if (!pcie->cfg->supports_system_suspend)
> + return 0;
> +
> + /* if the link is not in l1ss don't turn off clocks */
> + val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
> + if (!(val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
> + dev_warn(dev, "Link is not in L1ss\n");
> + return 0;
> + }

If anything, this looks like the version specific code.

> +
> + if (pcie->cfg->ops->suspend)
> + pcie->cfg->ops->suspend(pcie);
> +
> + pcie->is_suspended = true;
> +
> + return 0;
> +}
> +
> +static int __maybe_unused qcom_pcie_pm_resume(struct device *dev)
> +{
> + struct qcom_pcie *pcie = dev_get_drvdata(dev);
> +
> + if (!pcie->is_suspended)
> + return 0;

Pretty sure the driver core should take care of not calling resume if
not suspended.

> +
> + if (pcie->cfg->ops->resume)
> + pcie->cfg->ops->resume(pcie);
> +
> + pcie->is_suspended = false;
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops qcom_pcie_pm_ops = {
> + NOIRQ_SYSTEM_SLEEP_PM_OPS(qcom_pcie_pm_suspend, qcom_pcie_pm_resume)
> +};
> +
> static const struct of_device_id qcom_pcie_match[] = {
> { .compatible = "qcom,pcie-apq8084", .data = &apq8084_cfg },
> { .compatible = "qcom,pcie-ipq8064", .data = &ipq8064_cfg },
> @@ -1796,6 +1871,7 @@ static struct platform_driver qcom_pcie_driver = {
> .probe = qcom_pcie_probe,
> .driver = {
> .name = "qcom-pcie",
> + .pm = pm_sleep_ptr(&qcom_pcie_pm_ops),
> .suppress_bind_attrs = true,
> .of_match_table = qcom_pcie_match,
> },
> --
> 2.7.4
>