linux-kernel - Re: [PATCH v3 5/6] PCI: imx6: Add PLL clock lock check for i.MX95 PCIe

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Message-ID: <y3ys5ojt3cryklqibg4shznkjqije7bturs5ljkjyzbri5dhgu@jeo2mmyv7sci>
Date: Wed, 2 Apr 2025 12:40:23 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Richard Zhu <hongxing.zhu@....com>
Cc: frank.li@....com, l.stach@...gutronix.de, lpieralisi@...nel.org, 
	kw@...ux.com, robh@...nel.org, bhelgaas@...gle.com, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com, 
	linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, imx@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/6] PCI: imx6: Add PLL clock lock check for i.MX95
 PCIe

On Fri, Mar 28, 2025 at 11:02:12AM +0800, Richard Zhu wrote:
> Add PLL clock lock check for i.MX95 PCIe.
> 

What are the implications of not waiting for PLL lock? I guess clock
instability.

> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> Reviewed-by: Frank Li <Frank.Li@....com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 28 +++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 35194b543551..40eeb02ffb5d 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -45,6 +45,9 @@
>  #define IMX95_PCIE_PHY_GEN_CTRL			0x0
>  #define IMX95_PCIE_REF_USE_PAD			BIT(17)
>  
> +#define IMX95_PCIE_PHY_MPLLA_CTRL		0x10
> +#define IMX95_PCIE_PHY_MPLL_STATE		BIT(30)
> +
>  #define IMX95_PCIE_SS_RW_REG_0			0xf0
>  #define IMX95_PCIE_REF_CLKEN			BIT(23)
>  #define IMX95_PCIE_PHY_CR_PARA_SEL		BIT(9)
> @@ -479,6 +482,23 @@ static void imx7d_pcie_wait_for_phy_pll_lock(struct imx_pcie *imx_pcie)
>  		dev_err(dev, "PCIe PLL lock timeout\n");
>  }
>  
> +static int imx95_pcie_wait_for_phy_pll_lock(struct imx_pcie *imx_pcie)
> +{
> +	u32 val;
> +	struct device *dev = imx_pcie->pci->dev;
> +
> +	if (regmap_read_poll_timeout(imx_pcie->iomuxc_gpr,
> +				     IMX95_PCIE_PHY_MPLLA_CTRL, val,
> +				     val & IMX95_PCIE_PHY_MPLL_STATE,
> +				     PHY_PLL_LOCK_WAIT_USLEEP_MAX,
> +				     PHY_PLL_LOCK_WAIT_TIMEOUT)) {
> +		dev_err(dev, "PCIe PLL lock timeout\n");
> +		return -ENODEV;

-ETIMEDOUT

- Mani

-- 
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