[PATCH] PCI device-node failure detection

[Jake Moilanen]

> "fail" is not the only possible state that would indicate that the
> device is unusable, if I'm reading IEEE 1275 right.  There is also
> "disabled" and "fail-xxx" where xxx is additional info about the
> fault.  I've never seen "fail-xxx" myself but I've seen "disabled" on
> devices that were deconfigured by firmware (failing cpu iirc).

I haven't seen this on an adapter, but better to follow the spec.  

> Unless we want to treat "disabled" and "fail[-xxx]" differently, I
> think we should be checking that the status property, if present,
> says "okay".
> 
> Something like:
> 
> int dn_failed(struct device_node *dn)
> {
> 	char *status = get_property(dn, "status", NULL);
> 
> 	if (!status)
> 		return 0;
> 
> 	if (!strcmp(status, "okay"))
> 		return 0;
> 
> 	return 1;
> }

I like that much more.  

> Also, I think this function could be made a static helper in
> pSeries_pci.c until something outside of that file needs it.

Hmm...I thought we were trying to keep all device-tree specific items in
prom.c.  


Here's a fixed up version of the dn_failed().

Signed-off-by: Jake Moilanen <moilanen at austin.ibm.com>

Index: 2.6.12/arch/ppc64/kernel/prom.c
===================================================================
--- 2.6.12.orig/arch/ppc64/kernel/prom.c	2005-03-02 01:38:13.000000000 -0600
+++ 2.6.12/arch/ppc64/kernel/prom.c	2005-05-31 21:05:58.674114874 -0500
@@ -1887,6 +1887,22 @@
 	*next = prop;
 }
 
+int
+dn_failed(struct device_node * dn)
+{
+	char * status;
+
+	status = get_property(dn, "status", NULL);
+
+	if (!status)
+		return 0;
+
+	if (!strcmp(status, "okay"))
+		return 0;
+
+	return 1;
+}
+
 #if 0
 void
 print_properties(struct device_node *np)
Index: 2.6.12/arch/ppc64/kernel/pSeries_pci.c
===================================================================
--- 2.6.12.orig/arch/ppc64/kernel/pSeries_pci.c	2005-03-02 01:38:34.000000000 -0600
+++ 2.6.12/arch/ppc64/kernel/pSeries_pci.c	2005-05-27 18:44:33.000000000 -0500
@@ -96,7 +96,7 @@
 
 	/* Search only direct children of the bus */
 	for (dn = busdn->child; dn; dn = dn->sibling)
-		if (dn->devfn == devfn)
+		if (dn->devfn == devfn && !dn_failed(dn))
 			return rtas_read_config(dn, where, size, val);
 	return PCIBIOS_DEVICE_NOT_FOUND;
 }
@@ -138,7 +138,7 @@
 
 	/* Search only direct children of the bus */
 	for (dn = busdn->child; dn; dn = dn->sibling)
-		if (dn->devfn == devfn)
+		if (dn->devfn == devfn && !dn_failed(dn))
 			return rtas_write_config(dn, where, size, val);
 	return PCIBIOS_DEVICE_NOT_FOUND;
 }
Index: 2.6.12/include/asm-ppc64/prom.h
===================================================================
--- 2.6.12.orig/include/asm-ppc64/prom.h	2005-03-02 01:38:33.000000000 -0600
+++ 2.6.12/include/asm-ppc64/prom.h	2005-05-27 18:44:33.000000000 -0500
@@ -225,5 +225,6 @@
 extern int prom_n_intr_cells(struct device_node* np);
 extern void prom_get_irq_senses(unsigned char *senses, int off, int max);
 extern void prom_add_property(struct device_node* np, struct property* prop);
+extern int dn_failed(struct device_node * dn);
 
 #endif /* _PPC64_PROM_H */