On Fri, Jan 19, 2024 at 12:11:11PM -0500, Frank Li wrote:

Avoid use get slot id by compared with register physical address. If there
are more than 2 slots, compared logic will become complex.

"linux,pci-domain" already exist at dts since commit:
	commit (c0b70f05c87f3b arm64: dts: imx8mq: use_dt_domains for pci node).

So it is safe to remove compare basic address code:
	...
	if (dbi_base->start == IMX8MQ_PCIE2_BASE_ADDR)
		imx6_pcie->controller_id = 1;
	...

I have no idea what this is telling me.  I guess you don't want to use
IMX8MQ_PCIE2_BASE_ADDR to decide something?  That much sounds good:
the *address* of some MMIO space doesn't tell us anything about the
function of that space.

I expect the "compatible" string to tell the driver what the
programming model of the device is.

+	/* Using linux,pci-domain as PCI slot id */
+	imx6_pcie->controller_id = of_get_pci_domain_nr(node);
+	/*
+	 * If there are no "linux,pci-domain" property specified in DT, then assume only one
+	 * controller is available.
+	 */
+	if (imx6_pcie->controller_id == -EINVAL)
+		imx6_pcie->controller_id = 0;
+	else if (imx6_pcie->controller_id < 0)
+		return dev_err_probe(dev, imx6_pcie->controller_id,
+				     "linux,pci-domain have wrong value\n");

Maybe I'm missing something here.  It looks like this driver uses
controller_id to distinguish between hardware variants or maybe
between two Root Ports (slots?) in the same SoC?

  imx6_pcie_grp_offset
    return imx6_pcie->controller_id == 1 ? IOMUXC_GPR16 : IOMUXC_GPR14;

  imx6_pcie_configure_type
    id = imx6_pcie->controller_id
    if (!drvdata->mode_mask[id])         # <-- looks unsafe
      id = 0;
    regmap_update_bits(drvdata->mode_off[id], ...)

(This "mode_mask[id]" looks like it will reference garbage if the DT
supplies "linux,pci-domain = <2>".  A bogus DT shouldn't be able to
cause a driver to misbehave like that.)

That doesn't seem related to "linux,pci-domain" at all.

Bjorn

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