[Skiboot] [PATCH] core/pci: Prefer ibm, slot-label when finding loc codes

[Oliver O'Halloran]

On OpenPower systems the ibm,slot-label property is used to identify
slots rather than the more verbose ibm,slot-location-code. The
slot-label lookup is currently broken since it assumes that the
ibm,slot-label is in the PCI device node rather than in the node of the
device that provides the slot (e.g. root port or switch downstream
port).

This patch corrects the lookup code to search the parent node (and
possibly it's grandparents), similar to how we search for
ibm,slot-location-code.

Fixes: 1c3baae4f2b3 ("hdata/iohub: Look for IOVPD on P9")
Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
The Fixes: here is a bit mis-leading. It's been pretty much always
broken, but we never really noticed because on most systems the
slot-label and the slot-location-code are identical. 1c3baae4f2b3
caused them to differ because the PHB's base location code was
added to the DT which changes the generated slot-location-code to
include the PHB location code.
---
 core/pci.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/core/pci.c b/core/pci.c
index 57154b07474d..ee563c2fc577 100644
--- a/core/pci.c
+++ b/core/pci.c
@@ -1423,15 +1423,20 @@ static void pci_add_loc_code(struct dt_node *np, struct pci_device *pd)
 	uint8_t class, sub;
 	uint8_t pos, len;
 
-	/* If there is a label assigned to the function, use it on openpower machines */
-	if (pd->slot)
-		blcode = dt_prop_get_def(np, "ibm,slot-label", NULL);
+	while (p) {
+		/* if we have a slot label (i.e. openpower) use that */
+		blcode = dt_prop_get_def(p, "ibm,slot-label", NULL);
+		if (blcode)
+			break;
 
-	/* Look for a parent with a slot-location-code */
-	while (!blcode && p) {
+		/* otherwise use the fully qualified location code */
 		blcode = dt_prop_get_def(p, "ibm,slot-location-code", NULL);
+		if (blcode)
+			break;
+
 		p = p->parent;
 	}
+
 	if (!blcode)
 		return;
 
-- 
2.20.1