As we now have valid PCI host bridge device reference we can
introduce code that is going to find its bus domain number using
ACPI _SEG method.
Note that _SEG method is optional, therefore _SEG absence means
that all PCI buses belong to domain 0.
Signed-off-by: Tomasz Nowicki <tn@xxxxxxxxxxxx>
Reviewed-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
---
drivers/pci/pci.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7274006..39a985b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -25,6 +25,7 @@
#include <linux/device.h>
#include <linux/pm_runtime.h>
#include <linux/pci_hotplug.h>
+#include <linux/acpi.h>
#include <asm-generic/pci-bridge.h>
#include <asm/setup.h>
#include <linux/aer.h>
@@ -4796,14 +4797,34 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
* API and update the use_dt_domains value to keep track of method we
* are using to assign domain numbers (use_dt_domains = 0).
*
+ * IF ACPI, we expect non-DT method (use_dt_domains == -1)
+ * and call _SEG method for corresponding host bridge device.
+ * If _SEG method does not exist, following ACPI spec (6.5.6)
+ * all PCI buses belong to domain 0.
+ *
* All other combinations imply we have a platform that is trying
- * to mix domain numbers obtained from DT and pci_get_new_domain_nr(),
- * which is a recipe for domain mishandling and it is prevented by
- * invalidating the domain value (domain = -1) and printing a
- * corresponding error.
+ * to mix domain numbers obtained from DT, ACPI and
+ * pci_get_new_domain_nr(), which is a recipe for domain mishandling and
+ * it is prevented by invalidating the domain value (domain = -1) and
+ * printing a corresponding error.
*/
+
if (domain >= 0 && use_dt_domains) {
use_dt_domains = 1;
+#ifdef CONFIG_ACPI
+ } else if (!acpi_disabled && use_dt_domains == -1) {
+ struct acpi_device *acpi_dev = to_acpi_device(parent);
+ unsigned long long segment = 0;
+ acpi_status status;
+
+ status = acpi_evaluate_integer(acpi_dev->handle,
+ METHOD_NAME__SEG, NULL,
+ &segment);
+ if (ACPI_FAILURE(status) && status != AE_NOT_FOUND)
+ dev_err(&acpi_dev->dev, "can't evaluate _SEG\n");
+
+ domain = segment;
+#endif
} else if (domain < 0 && use_dt_domains != 1) {
use_dt_domains = 0;
domain = pci_get_new_domain_nr();
--
1.9.1
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