linux-kernel - Re: [PATCH v2 1/2] PCI: qcom: Add system PM support

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Message-ID: <20220630043415.GA5012@thinkpad>
Date:   Thu, 30 Jun 2022 10:04:15 +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_hemantk@...cinc.com,
        quic_nitegupt@...cinc.com, quic_skananth@...cinc.com,
        quic_ramkri@...cinc.com, swboyd@...omium.org,
        dmitry.baryshkov@...aro.org,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v2 1/2] PCI: qcom: Add system PM support

On Wed, Jun 29, 2022 at 03:03:33PM +0530, Krishna chaitanya chundru wrote:
> Add suspend and resume pm callbacks.
> 
> When system suspends, and if the link is in L1ss, disable the clocks
> so that system enters into low power state to save the maximum power.
> And when the system resumes, enable the clocks back if they are
> disabled in the suspend path.
> 

Why only during L1ss and not L2/L3?

> Changes since v1:
> 	- Fixed compilation errors.
> 
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 81 ++++++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 6ab9089..8e9ef37 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -41,6 +41,9 @@
>  #define L23_CLK_RMV_DIS				BIT(2)
>  #define L1_CLK_RMV_DIS				BIT(1)
>  
> +#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)
> @@ -190,6 +193,8 @@ 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 (*enable_clks)(struct qcom_pcie *pcie);
> +	int (*disable_clks)(struct qcom_pcie *pcie);

I think these could vary between platforms. Like some other platform may try to
disable regulators etc... So use names such as suspend and resume.

>  };
>  
>  struct qcom_pcie_cfg {
> @@ -199,6 +204,7 @@ 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 support_pm_ops:1;
>  };
>  
>  struct qcom_pcie {
> @@ -209,6 +215,7 @@ struct qcom_pcie {
>  	struct phy *phy;
>  	struct gpio_desc *reset;
>  	const struct qcom_pcie_cfg *cfg;
> +	unsigned int is_suspended:1;

Why do you need this flag? Is suspend going to happen multiple times in
an out-of-order manner?

>  };
>  
>  #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
> @@ -1308,6 +1315,23 @@ static void qcom_pcie_post_deinit_2_7_0(struct qcom_pcie *pcie)
>  	clk_disable_unprepare(res->pipe_clk);
>  }
>  

[...]

> +static const struct dev_pm_ops qcom_pcie_pm_ops = {
> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(qcom_pcie_pm_suspend, qcom_pcie_pm_resume)

Use the new macro: NOIRQ_SYSTEM_SLEEP_PM_OPS

> +};
> +
>  static const struct of_device_id qcom_pcie_match[] = {
>  	{ .compatible = "qcom,pcie-apq8084", .data = &apq8084_cfg },
>  	{ .compatible = "qcom,pcie-ipq8064", .data = &ipq8064_cfg },
> @@ -1679,6 +1759,7 @@ static struct platform_driver qcom_pcie_driver = {
>  	.probe = qcom_pcie_probe,
>  	.driver = {
>  		.name = "qcom-pcie",
> +		.pm = &qcom_pcie_pm_ops,

There will be warnings when CONFIG_PM_SLEEP is not set. So use below,

		.pm = pm_sleep_ptr(&qcom_pcie_pm_ops),

Thanks,
Mani

>  		.suppress_bind_attrs = true,
>  		.of_match_table = qcom_pcie_match,
>  	},
> -- 
> 2.7.4
> 

-- 
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