On Tue, Mar 11, 2025 at 01:11:04AM +0000, Hongxing Zhu wrote:

quoted

-----Original Message-----
From: Bjorn Helgaas <helgaas@kernel.org>
Sent: 2025年3月10日 23:11
To: Hongxing Zhu <hongxing.zhu@nxp.com>
Cc: robh@kernel.org; krzk+dt@kernel.org; conor+dt@kernel.org;
shawnguo@kernel.org; l.stach@pengutronix.de; lpieralisi@kernel.org;
kw@linux.com; manivannan.sadhasivam@linaro.org; bhelgaas@google.com;
s.hauer@pengutronix.de; festevam@gmail.com; devicetree@vger.kernel.org;
linux-pci@vger.kernel.org; imx@lists.linux.dev; kernel@pengutronix.de;
linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 2/2] PCI: imx6: Use domain number replace the
hardcodes

On Wed, Feb 26, 2025 at 10:42:56AM +0800, Richard Zhu wrote:

quoted

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)

quoted

 	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)

quoted

 			return PTR_ERR(imx_pcie->phy_base);
 	}

-	pci->dbi_base = devm_platform_get_and_ioremap_resource(pdev, 0,

&dbi_base);

quoted

-	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?

Hi Bjorn:
Thanks for your concerns.
Don't worry about the assignment of pci->dbi_base.
If pci-imx6.c driver doesn't set it. DWC core driver would set it when
 dw_pcie_get_resources() is invoked.

Great, thanks!  Maybe we can amend the commit log to mention that and
the new "linux,pci-domain" dependency.