It seems some old Sundace(now IC Plus Corp.) controllers do not

like memory mapped register access. Typical problem from the issue
was MII access returned unreliable values. I'm not sure this comes
from lack of register flushing in MII access after accessing
STE_PHYCTL register though.
To address the issue, read hints data that controls which type of
memory mapping should be used in driver. ste(4) still prefers
memory mapping to io mapping but honor hints entered by user except
for controllers that have problems with memory mapping.
The hint to use iomapping could be given by adding the following
line to /boot/device.hints file.

hint.ste.0.prefer_iomap="1"

PR:	kern/149285
MFC after:	5 days

1 files changed, 20 insertions, 7 deletions

diff --git a/sys/dev/ste/if_ste.c b/sys/dev/ste/if_ste.c
index 78c0290b70a0..e3297e6d5735 100644
--- a/sys/dev/ste/if_ste.c
+++ b/sys/dev/ste/if_ste.c
@@ -1059,7 +1059,7 @@ ste_attach(device_t dev)
 	struct ste_softc *sc;
 	struct ifnet *ifp;
 	uint16_t eaddr[ETHER_ADDR_LEN / 2];
-	int error = 0, pmc, rid;
+	int error = 0, pmc, prefer_iomap, rid;
 
 	sc = device_get_softc(dev);
 	sc->ste_dev = dev;
@@ -1081,12 +1081,25 @@ ste_attach(device_t dev)
 	 */
 	pci_enable_busmaster(dev);
 
-	/* Prefer memory space register mapping over IO space. */
-	sc->ste_res_id = PCIR_BAR(1);
-	sc->ste_res_type = SYS_RES_MEMORY;
-	sc->ste_res = bus_alloc_resource_any(dev, sc->ste_res_type,
-	    &sc->ste_res_id, RF_ACTIVE);
-	if (sc->ste_res == NULL) {
+	/*
+	 * Prefer memory space register mapping over IO space but use
+	 * IO space for a device that is known to have issues on memory
+	 * mapping.
+	 */
+	prefer_iomap = 0;
+	if (pci_get_device(dev) == ST_DEVICEID_ST201_1)
+		prefer_iomap = 1;
+	else
+		resource_int_value(device_get_name(sc->ste_dev),
+		    device_get_unit(sc->ste_dev), "prefer_iomap",
+		    &prefer_iomap);
+	if (prefer_iomap == 0) {
+		sc->ste_res_id = PCIR_BAR(1);
+		sc->ste_res_type = SYS_RES_MEMORY;
+		sc->ste_res = bus_alloc_resource_any(dev, sc->ste_res_type,
+		    &sc->ste_res_id, RF_ACTIVE);
+	}
+	if (prefer_iomap || sc->ste_res == NULL) {
 		sc->ste_res_id = PCIR_BAR(0);
 		sc->ste_res_type = SYS_RES_IOPORT;
 		sc->ste_res = bus_alloc_resource_any(dev, sc->ste_res_type,