On Wed, 2026-07-08 at 05:16 +0800, Miao Wang via B4 Relay wrote: > From: Miao Wang <[email protected]> > > The reset event of BMC is captured through GPIO. However, this driver > bypasses the GPIO framework and directly accesses the GPIO controller > through the fixed address. When the same GPIO controller is also > exposed through ACPI and probed by the corresponding GPIO driver, > there would be a conflict between the two drivers. > > This patch will try to find the GPIO through declared GPIO pin in the > _CRS resources of the ACPI node. If no such delaration is found, the > driver will fall back to search for the correct GPIO controller and pin > according to the fixed address and pin number. A possible DSDT > declaration for the GPIO pin might be as follows: > > Device (BMC0) { > Name (_ADR, ...) // Match the PCI address of the BMC device > // \_SB.GPO1 is the ACPI path of the GPIO controller > Name (_CRS, ResourceTemplate () { > GpioInt (Edge, ActiveLow, Exclusive, PullNone, 0, > "\\_SB.GPO1", 0) { > 14 // 14 is the GPIO pin number > } > }
I think this is a proposal without real implementation yet? If so... /* snip */ > + adev = to_acpi_device_node(fwnode); > + if (!adev) > + goto out; > + > + INIT_LIST_HEAD(&resource_list); > + > + ret = acpi_dev_get_memory_resources(adev, &resource_list); > + if (ret < 0) > + goto out; > + rentry = list_first_entry_or_null(&resource_list, struct > resource_entry, node); > + if (!rentry) > + goto free_resource_list; > + if (rentry->res->start == start_addr) > + found = 1; > + > +free_resource_list: > + acpi_dev_free_resource_list(&resource_list); ... consider adding a _DSD method to label (like "bmc-reset") the GPIO for the proposed BMC0 device so you can use devm_gpiod_get to get the GPIO, instead of using the hand-brew code to parse the ACPI node. See https://www.kernel.org/doc/html/latest/firmware-guide/acpi/gpio-properties.html. Combining this with Bartosz's comment, the logic would be like: if (missing the ACPI node) assign a swnode to label "gpio14" as "bmc-reset"; gpio_desc = devm_gpiod_get(&dev, "bmc-reset", GPIOD_IN); And such a proposal will need to be discussed with Loongson. Yes I know people may hate the "control" from the vendor, but having some effectively dead code (i.e. supporting some non-exist firmware) in the kernel is worse. -- Xi Ruoyao <[email protected]> _______________________________________________ Openipmi-developer mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/openipmi-developer
