Re: [PATCH v1 2/2] PCI: imx6: Use domain number replace the hardcodes

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Feb 26, 2025 at 10:42:56AM +0800, Richard Zhu wrote:
> Use the domain number replace the hardcodes to uniquely identify
> different controller on i.MX8MQ platforms. No function changes.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 90ace941090f..ab9ebb783593 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -41,7 +41,6 @@
>  #define IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE	BIT(11)
>  #define IMX8MQ_GPR_PCIE_VREG_BYPASS		BIT(12)
>  #define IMX8MQ_GPR12_PCIE2_CTRL_DEVICE_TYPE	GENMASK(11, 8)
> -#define IMX8MQ_PCIE2_BASE_ADDR			0x33c00000
>  
>  #define IMX95_PCIE_PHY_GEN_CTRL			0x0
>  #define IMX95_PCIE_REF_USE_PAD			BIT(17)
> @@ -1474,7 +1473,6 @@ static int imx_pcie_probe(struct platform_device *pdev)
>  	struct dw_pcie *pci;
>  	struct imx_pcie *imx_pcie;
>  	struct device_node *np;
> -	struct resource *dbi_base;
>  	struct device_node *node = dev->of_node;
>  	int i, ret, req_cnt;
>  	u16 val;
> @@ -1515,10 +1513,6 @@ static int imx_pcie_probe(struct platform_device *pdev)
>  			return PTR_ERR(imx_pcie->phy_base);
>  	}
>  
> -	pci->dbi_base = devm_platform_get_and_ioremap_resource(pdev, 0, &dbi_base);
> -	if (IS_ERR(pci->dbi_base))
> -		return PTR_ERR(pci->dbi_base);

This makes me wonder.

IIUC this means that previously we set controller_id to 1 if the first
item in devicetree "reg" was 0x33c00000, and now we will set
controller_id to 1 if the devicetree "linux,pci-domain" property is 1.
This is good, but I think this new dependency on the correct
"linux,pci-domain" in devicetree should be mentioned in the commit
log.

My bigger worry is that we no longer set pci->dbi_base at all.  I see
that the only use of pci->dbi_base in pci-imx6.c was to determine the
controller_id, but this is a DWC-based driver, and the DWC core
certainly uses pci->dbi_base.  Are we sure that none of those DWC core
paths are important to pci-imx6.c?

>  	/* Fetch GPIOs */
>  	imx_pcie->reset_gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>  	if (IS_ERR(imx_pcie->reset_gpiod))
> @@ -1565,8 +1559,12 @@ static int imx_pcie_probe(struct platform_device *pdev)
>  	switch (imx_pcie->drvdata->variant) {
>  	case IMX8MQ:
>  	case IMX8MQ_EP:
> -		if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
> -			imx_pcie->controller_id = 1;
> +		ret = of_get_pci_domain_nr(node);
> +		if (ret < 0 || ret > 1)
> +			return dev_err_probe(dev, -ENODEV,
> +					     "failed to get valid pcie domain\n");
> +		else
> +			imx_pcie->controller_id = ret;
>  		break;
>  	default:
>  		break;
> -- 
> 2.37.1
>