linux-kernel - Re: [PATCH v7 02/16] PCI: imx6: Simplify phy handling by using by using IMX6_PCIE_FLAG_HAS

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Message-ID: <20240106153323.GE2512@thinkpad>
Date: Sat, 6 Jan 2024 21:03:23 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.Li@....com>
Cc: krzysztof.kozlowski@...aro.org, bhelgaas@...gle.com,
	conor+dt@...nel.org, devicetree@...r.kernel.org, festevam@...il.com,
	helgaas@...nel.org, hongxing.zhu@....com, imx@...ts.linux.dev,
	kernel@...gutronix.de, krzysztof.kozlowski+dt@...aro.org,
	kw@...ux.com, l.stach@...gutronix.de,
	linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	lpieralisi@...nel.org, robh@...nel.org, s.hauer@...gutronix.de,
	shawnguo@...nel.org
Subject: Re: [PATCH v7 02/16] PCI: imx6: Simplify phy handling by using by
 using IMX6_PCIE_FLAG_HAS_PHY

On Wed, Dec 27, 2023 at 01:27:13PM -0500, Frank Li wrote:
> Refactors the phy handling logic in the imx6 PCI driver by adding
> IMX6_PCIE_FLAG_HAS_PHY bitmask define for drvdata::flags.
> 
> The drvdata::flags and a bitmask ensures a cleaner and more scalable
> switch-case structure for handling phy.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> 
> Notes:
>     Change from v4 to v5:
>     - none, Keep IMX6_PCIE_FLAG_HAS_PHY to indicate dts mismatch when platform
>     require phy suppport.
>     
>     Change from v1 to v3:
>     - none
> 
>  drivers/pci/controller/dwc/pci-imx6.c | 23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 50d9faaa17f71..4d620249f3d52 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -60,6 +60,9 @@ enum imx6_pcie_variants {
>  #define IMX6_PCIE_FLAG_IMX6_PHY			BIT(0)
>  #define IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE	BIT(1)
>  #define IMX6_PCIE_FLAG_SUPPORTS_SUSPEND		BIT(2)
> +#define IMX6_PCIE_FLAG_HAS_PHY			BIT(3)

Every PCIe setup requires PHY for its operation. Perhaps you are referring to
external PHY? If so, please rename this to IMX6_PCIE_FLAG_HAS_EXT_PHY.

> +
> +#define imx6_check_flag(pci, val)     (pci->drvdata->flags & val)
>  
>  #define IMX6_PCIE_MAX_CLKS       6
>  
> @@ -1277,6 +1280,13 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	if (imx6_check_flag(imx6_pcie, IMX6_PCIE_FLAG_HAS_PHY)) {

IMO, we would not need these kind of checks in the driver if the DT binding is
properly validated using schema. But folks always want to validate "broken DT"
in the drivers :(

But I'm fine with this check for now since not everyone agree with above.

- Mani

> +		imx6_pcie->phy = devm_phy_get(dev, "pcie-phy");
> +		if (IS_ERR(imx6_pcie->phy))
> +			return dev_err_probe(dev, PTR_ERR(imx6_pcie->phy),
> +					     "failed to get pcie phy\n");
> +	}
> +
>  	switch (imx6_pcie->drvdata->variant) {
>  	case IMX7D:
>  		if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> @@ -1306,11 +1316,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  			return dev_err_probe(dev, PTR_ERR(imx6_pcie->apps_reset),
>  					     "failed to get pcie apps reset control\n");
>  
> -		imx6_pcie->phy = devm_phy_get(dev, "pcie-phy");
> -		if (IS_ERR(imx6_pcie->phy))
> -			return dev_err_probe(dev, PTR_ERR(imx6_pcie->phy),
> -					     "failed to get pcie phy\n");
> -
>  		break;
>  	default:
>  		break;
> @@ -1444,13 +1449,15 @@ static const struct imx6_pcie_drvdata drvdata[] = {
>  	},
>  	[IMX8MM] = {
>  		.variant = IMX8MM,
> -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> +			 IMX6_PCIE_FLAG_HAS_PHY,
>  		.gpr = "fsl,imx8mm-iomuxc-gpr",
>  		.clk_names = {"pcie_bus", "pcie", "pcie_aux"},
>  	},
>  	[IMX8MP] = {
>  		.variant = IMX8MP,
> -		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND,
> +		.flags = IMX6_PCIE_FLAG_SUPPORTS_SUSPEND |
> +			 IMX6_PCIE_FLAG_HAS_PHY,
>  		.gpr = "fsl,imx8mp-iomuxc-gpr",
>  		.clk_names = {"pcie_bus", "pcie", "pcie_aux"},
>  	},
> @@ -1462,12 +1469,14 @@ static const struct imx6_pcie_drvdata drvdata[] = {
>  	},
>  	[IMX8MM_EP] = {
>  		.variant = IMX8MM_EP,
> +		.flags = IMX6_PCIE_FLAG_HAS_PHY,
>  		.mode = DW_PCIE_EP_TYPE,
>  		.gpr = "fsl,imx8mm-iomuxc-gpr",
>  		.clk_names = {"pcie_bus", "pcie", "pcie_aux"},
>  	},
>  	[IMX8MP_EP] = {
>  		.variant = IMX8MP_EP,
> +		.flags = IMX6_PCIE_FLAG_HAS_PHY,
>  		.mode = DW_PCIE_EP_TYPE,
>  		.gpr = "fsl,imx8mp-iomuxc-gpr",
>  		.clk_names = {"pcie_bus", "pcie", "pcie_aux"},
> -- 
> 2.34.1
> 

-- 
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