Subject: Re: [PATCH 1/6] powerpc/eeh: Don't collect PCI-CFG data on PHB

From: Gavin Shan <[email-masked]>
Date: Wed, 26 Jun 2013 07:49:17 +0800

On Tue, Jun 25, 2013 at 09:55:15PM +1000, Benjamin Herrenschmidt wrote:
>On Tue, 2013-06-25 at 18:00 +0800, Gavin Shan wrote:
>> +       /*
>> +        * When the PHB is fenced or dead, it's pointless to collect
>> +        * the data from PCI config space because it should return
>> +        * 0xFF's. For ER, we still retrieve the data from the PCI
>> +        * config space.
>> +        */
>> +       if (eeh_probe_mode_dev() &&
>> +           (pe->type & EEH_PE_PHB) &&
>> +           (pe->state & (EEH_PE_ISOLATED | EEH_PE_PHB_DEAD)))
>> +               valid_cfg_log = false;
>> +
>
>I'm still unsure about that one. EEH_PE_ISOLATED could be the result
>of a normal ER of PE#0 (which can happen for various reasons other
>than a fence) in which case the config space is available and
>interesting.
>

It's something like the followings. For ER on PE#0, we will have
PE with type of EEH_PE_BUS marked as isolated, instead of the
one with EEH_PE_PHB.

	[ EEH_PE_PHB] <---> [ EEH_PE_PHB] <---> [ EEH_PE_PHB]
				  |
			    [ EEH_PE_BUS ] PE#0
				  |
		        -------------------------
			|			|
		   [ EEH_PE_BUS ] PE#1	   [ EEH_PE_BUS] PE#2

>I would either not bother and collect the FF's, or make this specific
>to fence and only fence.
>

I'd like to keep it specific to fenced PHB and it's already be that :-)

Thanks,
Gavin