# HG changeset patch
# User Taylor R Campbell <riastradh@NetBSD.org>
# Date 1741026655 0
#      Mon Mar 03 18:30:55 2025 +0000
# Branch trunk
# Node ID 8be0c360379cd914719f2e6a7ac3326431b8c7d8
# Parent  6ecb83a403406fc7d3cffc0d01cf9d0baf3cb22c
# EXP-Topic riastradh-pr59118-x86pciresman
acpimcfg(4): Use bus ranges set in _CRS if available.

Use the MCFG bus range only as a fallback.  The _CRS should tell us
what ranges are available for us to use, which may not even be
contiguous (which pci_resource(9) currently doesn't handle but we'll
deal with that in a separate commit).

PR port-amd64/59118: Thinkpad T495s - iwm PCI BAR is zero

diff -r 6ecb83a40340 -r 8be0c360379c sys/dev/acpi/acpi_mcfg.c
--- a/sys/dev/acpi/acpi_mcfg.c	Mon Mar 03 18:13:32 2025 +0000
+++ b/sys/dev/acpi/acpi_mcfg.c	Mon Mar 03 18:30:55 2025 +0000
@@ -683,10 +683,16 @@ out:
 }
 
 #ifdef PCI_RESOURCE
+struct acpimcfg_configure_bus_context {
+	struct pci_resource_info pciinfo;
+	bool bus_found;
+};
+
 ACPI_STATUS
 acpimcfg_configure_bus_cb(ACPI_RESOURCE *res, void *ctx)
 {
-	struct pci_resource_info *pciinfo = ctx;
+	struct acpimcfg_configure_bus_context *C = ctx;
+	struct pci_resource_info *pciinfo = &C->pciinfo;
 	bus_addr_t addr;
 	bus_size_t size;
 	int type;
@@ -756,6 +762,8 @@ acpimcfg_configure_bus_cb(ACPI_RESOURCE 
 
 	if (size > 0) {
 		pci_resource_add_range(pciinfo, type, addr, addr + size - 1);
+		if (type == PCI_RANGE_BUS)
+			C->bus_found = true;
 	}
 
 	return AE_OK;
@@ -765,7 +773,7 @@ int
 acpimcfg_configure_bus(device_t self, pci_chipset_tag_t pc, ACPI_HANDLE handle,
     int bus, bool mapcfgspace)
 {
-	struct pci_resource_info pciinfo;
+	struct acpimcfg_configure_bus_context context, *C = &context;
 	struct mcfg_segment *seg;
 	struct mcfg_bus *mb;
 	bus_space_handle_t bsh[256];
@@ -821,20 +829,32 @@ acpimcfg_configure_bus(device_t self, pc
 		endbus = 255;
 	}
 
-	memset(&pciinfo, 0, sizeof(pciinfo));
-	pciinfo.pc = pc;
-	pci_resource_add_range(&pciinfo, PCI_RANGE_BUS, bus, endbus);
+	memset(C, 0, sizeof(*C));
+	C->pciinfo.pc = pc;
 	rv = AcpiWalkResources(handle, "_CRS", acpimcfg_configure_bus_cb,
-	    &pciinfo);
+	    &C->pciinfo);
 	if (ACPI_FAILURE(rv)) {
 		aprint_debug_dev(acpi_sc->sc_dev, "MCFG: Walk _CRS: %ld\n",
 		    (long)rv);
 		error = ENXIO;
 		goto cleanup;
 	}
+
+	/*
+	 * Paranoia: In case _CRS didn't list any bus ranges, guess
+	 * from the MCFG.
+	 */
+	if (!C->bus_found) {
+		aprint_error_dev(acpi_sc->sc_dev,
+		    "no PCI bus range in _CRS, guessing %d-%d from MCFG\n",
+		    bus, endbus);
+		pci_resource_add_range(&C->pciinfo, PCI_RANGE_BUS,
+		    bus, endbus);
+	}
+
 	error = 0;
 
-	pci_resource_init(&pciinfo);
+	pci_resource_init(&C->pciinfo);
 
 cleanup:
 	if (mapcfgspace) {