[coreboot] PCI MMCONF on amdfam10

Aaron Durbin adurbin at chromium.org
Fri Dec 13 05:01:25 CET 2013


On Thu, Dec 12, 2013 at 5:46 PM, ron minnich <rminnich at gmail.com> wrote:
> Which is why I always worry about global changes of this sort when
> they can't be tested.
>
> Things like this that *should* work, and look very reasonable, can at
> times get nasty.

To be fair, those static pci devices should have their access mode
fixed (a la pci_bus_operations) to the appropriate type instead of
relying on a global assumption. I think missing some corner cases is
vastly different than breaking a build.

That said, I have a feeling the probing method probably needs to be
tweaked to accommodate these cases in some manner.

>
> ron
>
> On Thu, Dec 12, 2013 at 3:34 PM, Stefan Reinauer
> <stefan.reinauer at coreboot.org> wrote:
>> * Kyösti Mälkki <kyosti.malkki at gmail.com> [131212 16:02]:
>>> Hi
>>>
>>> After commit 872c922 there is some trouble on PCI configuration
>>> access with Asus M4A785-M. This could apply to other amdfam10 too,
>>> although I have not yet received such reports.
>>>
>>> As the commit message stated, I had discovered that in the beginning
>>> of ramstage all PCI configuration access used the IO (0xcf8) method
>>> even though Kconfig specified MMCONF_SUPPORT_DEFAULT which should
>>> imply all PCI config access is done with MMCONF unless IO is
>>> explicitly requested.
>>
>> Not sure if this is relevant, but on i945 not all PCI devices are
>> visible in MMCONF space. So enabling MMCONF_SUPPORT_DEFAULT there will
>> break the system.
>>
>> Stefan
>>
>>
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>
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