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

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Message-ID: <20220211091409.GB3223@thinkpad>
Date:   Fri, 11 Feb 2022 14:44:09 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Prasad Malisetty <quic_pmaliset@...cinc.com>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org,
        lorenzo.pieralisi@....com, robh@...nel.org, kw@...ux.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
        swboyd@...omium.org
Subject: Re: [PATCH v2] PCI: qcom: Add system PM support

On top of Bjorn's review:

On Tue, Feb 01, 2022 at 11:37:56PM +0530, Prasad Malisetty wrote:
> Add suspend_noirq and resume_noirq callbacks to handle
> System suspend and resume in dwc pcie controller driver.
> 
> When system suspends, send PME turnoff message to enter
> link into L2 state. Along with powerdown the PHY, disable
> pipe clock, switch gcc_pcie_1_pipe_clk_src to XO if mux is
> supported and disable the pcie clocks, regulators.
> 
> When system resumes, PCIe link will be re-established and
> setup rc settings.
> 
> Signed-off-by: Prasad Malisetty <quic_pmaliset@...cinc.com>
> Reported-by: kernel test robot <lkp@...el.com>
> 
> ---
> Changes since v1:
> 	- Removed unnecessary logs and modified log level suggested by Manivannan.
> 	- Removed platform specific callbacks as PM support is generic.

This is not still generic... Please see below.

> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 97 ++++++++++++++++++++++++++++++++++
>  1 file changed, 97 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index c19cd506..d1dd6c7 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -73,6 +73,8 @@
>  
>  #define PCIE20_PARF_Q2A_FLUSH			0x1AC
>  
> +#define PCIE20_PARF_PM_STTS                     0x24
> +
>  #define PCIE20_MISC_CONTROL_1_REG		0x8BC
>  #define DBI_RO_WR_EN				1
>  
> @@ -1616,6 +1618,100 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  	return ret;
>  }
>  
> +static int qcom_pcie_send_pme_turnoff_msg(struct qcom_pcie *pcie)
> +{
> +	int ret = 0;
> +	u32 val = 0, poll_val = 0;
> +	u64 l23_rdy_poll_timeout = 100000;
> +	struct dw_pcie *pci = pcie->pci;
> +	struct device *dev = pci->dev;
> +
> +	val = readl(pcie->elbi + PCIE20_ELBI_SYS_CTRL);
> +	val |= BIT(4);

Define BIT(4)

> +	writel(val, pcie->elbi + PCIE20_ELBI_SYS_CTRL);
> +
> +	ret = readl_poll_timeout((pcie->parf + PCIE20_PARF_PM_STTS), poll_val,
> +			(poll_val & BIT(5)), 10000, l23_rdy_poll_timeout);

Define BIT(5)

> +	if (!ret)
> +		dev_info(dev, "PM_Enter_L23 is received\n");

Maybe print, "Device entered L23_Ready state"? Also this should be dev_dbg().

> +	else
> +		dev_err(dev, "PM_Enter_L23 is NOT received.PARF_PM_STTS 0x%x\n",

Maybe print, "Device failed to enter L23_Ready state"?

> +			readl_relaxed(pcie->parf + PCIE20_PARF_PM_STTS));
> +
> +	return ret;
> +}
> +
> +static void qcom_pcie_host_disable(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> +

As Bjorn said this would only work for platforms supporting v2.7.0 ops. Please
make it generic.

> +	/* Assert the reset of endpoint */
> +	qcom_ep_reset_assert(pcie);
> +
> +	/* Put PHY into POWER DOWN state */
> +	phy_power_off(pcie->phy);
> +
> +	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);

Define "1".

Thanks,
Mani