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