Subject: Re: [PATCH] Restore PERR/SERR bit settings during EEH device recovery

From: Mike Mason <[email-masked]>
Date: Tue, 08 Jul 2008 08:56:34 -0700

Linas Vepstas wrote:
> 2008/7/7 Mike Mason <[email-masked]>:
>> The following patch restores the PERR and SERR bits in the PCI
>> command register during an EEH device recovery.
>> We have found at least one case (an Agilent test card) where the
>> PERR/SERR bits are set to 1 by firmware at boot time, but are
>> not restored to 1 during EEH recovery.
> 
> Any chance they should be zero, and were accidentally set to 1?
> In which case, you'd need an else clause, below.

I suppose it's possible.  I'll add your suggestion and resubmit.

Mike

> 
>> The patch fixes the
>> Agilent card problem.  It has been tested on several other EEH-enabled cards
>> with no regressions.
>>
>> Signed-off-by: Mike Mason <[email-masked]>
>>
>> --- linux-2.6.26-rc9/arch/powerpc/platforms/pseries/eeh.c       2008-07-07
>> 16:06:57.000000000 -0700
>> +++ linux-2.6.26-rc9-new/arch/powerpc/platforms/pseries/eeh.c   2008-07-07
>> 16:11:10.000000000 -0700
>> @@ -812,6 +812,7 @@
>> static inline void __restore_bars (struct pci_dn *pdn)
>> {
>>        int i;
>> +       u32 cmd;
>>
>>        if (NULL==pdn->phb) return;
>>        for (i=4; i<10; i++) {
>> @@ -832,6 +833,15 @@
>>
>>        /* max latency, min grant, interrupt pin and line */
>>        rtas_write_config(pdn, 15*4, 4, pdn->config_space[15]);
>> +
>> +       /* Restore PERR & SERR bits, some devices require it,
>> +          don't touch the other command bits */
>> +       rtas_read_config(pdn, PCI_COMMAND, 4, &cmd);
>> +       if (pdn->config_space[1] & PCI_COMMAND_PARITY)
>> +               cmd |= PCI_COMMAND_PARITY;
> 
> else cmd &= ~PCI_COMMAND_PARITY;
> 
>> +       if (pdn->config_space[1] & PCI_COMMAND_SERR)
>> +               cmd |= PCI_COMMAND_SERR;
> 
> else cmd &= ~PCI_COMMAND_SERR;
> 
>> +       rtas_write_config(pdn, PCI_COMMAND, 4, cmd);
>> }
> 
> Other than that, I'll add an
> 
> Acked-by: Linas Vepstas <[email-masked]>
> 
> --linas