Fix nexus_pcib_is_host_bridge() so that it detects my 486's PCI bus

correctly. It has the following code:

        if (class != PCIC_BRIDGE || subclass != PCIS_BRIDGE_HOST)
                return NULL;

My 486 has an Integrated Micro Solutions PCI bridge which identifies
itself as subclass PCIS_BRIDGE_OTHER, not PCIS_BRIDGE_HOST. Consequently,
it gets ignored. In my opinion, the correct test should be:

        if ((class != PCIC_BRIDGE) && (subclass != PCIS_BRIDGE_HOST))
                return NULL;

That way the test still succeeds because the chip's class is PCIC_BRIDGE.
Clearly it's not reasonable to expect all host to PCI bridges to always
have a subclass of PCIS_BRIDGE_HOST since I've got one that doesn't.
This way the sanity test should remain relatively sane while still allowing
some oddball yet correct hardware to work. If somebody has a better way
to do it, go ahead and tweak the test, but be aware that
class == PCIC_BRIDGE and subclass == PCIS_BRIDGE_OTHER is a valid case.

While I was here, I also added an explicit ID string for the IMS chipset.
I also dealt with a minor style nit: it's bad karma not to have a default
case for your switch statements, but the one in this routine doesn't have
one. The default string of "Host to PCI bridge" is now assigned in a
default case of the switch statement instead of initializing "s" with the
string before the switch and then not having any default case.

1 files changed, 9 insertions, 3 deletions

diff --git a/sys/amd64/pci/pci_bus.c b/sys/amd64/pci/pci_bus.c
index eb6cc27..944d106 100644
--- a/sys/amd64/pci/pci_bus.c
+++ b/sys/amd64/pci/pci_bus.c
@@ -23,7 +23,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $Id: pcibus.c,v 1.43 1999/07/16 01:00:29 msmith Exp $
+ * $Id: pcibus.c,v 1.44 1999/08/04 13:38:24 peter Exp $
  *
  */
 
@@ -274,10 +274,10 @@ nexus_pcib_is_host_bridge(pcicfgregs *cfg,
 			  u_int32_t id, u_int8_t class, u_int8_t subclass,
 			  u_int8_t *busnum)
 {
-	const char *s = "Host to PCI bridge";
+	const char *s = NULL;
 	static u_int8_t pxb[4];	/* hack for 450nx */
 
-	if (class != PCIC_BRIDGE || subclass != PCIS_BRIDGE_HOST)
+	if ((class != PCIC_BRIDGE) && (subclass != PCIS_BRIDGE_HOST))
 		return NULL;
 
 	*busnum = 0;
@@ -395,6 +395,12 @@ nexus_pcib_is_host_bridge(pcicfgregs *cfg,
 		/* just guessing the secondary bus register number ... */
 		*busnum = pci_cfgread(cfg, 0x45, 1);
 		break;
+	case 0x884910e0:
+		s = "Integrated Micro Solutions VL Bridge";
+		break;
+	default:
+		s = "Host to PCI bridge";
+		break;
 	}
 
 	return s;