Re: [PATCH v7 39/50] powerpc/powernv: Fundamental reset in pnv_pci_reset_secondary_bus()

On Fri, Nov 13, 2015 at 11:08:29AM +1100, Daniel Axtens wrote:

Gavin Shan [off-list ref] writes:

quoted

 void pnv_pci_reset_secondary_bus(struct pci_dev *dev)
 {
-	pnv_eeh_bridge_reset(dev, EEH_RESET_HOT);
+	int option, freset = 0;
+
+	if (dev->subordinate)
+		pci_walk_bus(dev->subordinate,
+			     pnv_pci_dev_reset_type, &freset);
+
+	option = freset ? EEH_RESET_FUNDAMENTAL : EEH_RESET_HOT;
+	pnv_eeh_bridge_reset(dev, option);

According to the skiboot sources, fundamental reset isn't supported on
p5ioc2. As far as I can tell from your corresponding skiboot patches,
this is still the case after they are applied. Do we need a fallback to
EEH_RESET_HOT in this case? Otherwise there will be no reset performed
at all.

Likewise, if the FUNDAMENTAL reset fails for any reason, should we fall
back to a HOT reset?

P5IOC2 won't export any PCI slots. So kernel won't issue fundamental reset
to PCI buses on P5IOC2.

We had the failback: hot reset is picked if fundamental reset can't be
supported on the target PCI bus. In case fundamental reset fails, we
shouldn't go ahead try hot reset.

Thanks,
Gavin

Regards,
Daniel