[coreboot] PCI MMCONF on amdfam10

[ron minnich]

Thanks, Kyosti, sounds like you're on top of it :-)

ron

On Mon, Dec 16, 2013 at 9:17 PM, Kyösti Mälkki <kyosti.malkki at gmail.com> wrote:
> On 12/16/2013 10:35 PM, ron minnich wrote:
>>
>> On Fri, Dec 13, 2013 at 2:29 AM, Kyösti Mälkki <kyosti.malkki at gmail.com>
>> wrote:
>>
>>> Yet we have had commit 032c23db for 5 months:
>>
>>
>> which may mean, only, that the commit broke some things and nobody hit
>> those things until 5 months later?
>>
>> Which is not at all unusual with a change of this type. It's why we
>> prefer that commits that are this far-reaching come with some amount
>> of testing.
>> That patch changed 7 mainboards; which of them were tested?
>>
>
> Before merge, test on kontron/986-lcd-m as was recorded here:
> http://review.coreboot.org/#/c/3584/
>
> Also lenovo x60 and t60 boards have been often built from master during the
> last 5 months.
>
>
>
>>> I remember a week or so after this was merged you made that comment about
>>> i945 on a related change. I requested literature reference or a test case
>>> to
>>> see if I should revert. I got neither and the revert never took place.
>>
>>
>> It pays to listen to Stefan on matters such as these :-)
>>
>> There are at least two reasons that your request might not have been
>> satisfiable.
>> - the public docs and the hardware disagree (very common)
>> - the public docs and the NDA docs disagree (this is very common)
>>     and the vendor knows it (also really common)
>>
>>> Until you are  more specific on your statement, I am reading it as
>>> follows:
>>>
>>>    Stefan added 'select MMCONF_SUPPORT_DEFAULT' on a mainboard with i945
>>>    and the board did not boot.
>>
>>
>> And sometimes that's about as good a diagnosis as you can get.
>>
>> Expecting anything more is not always realistic. That's what makes
>> firmware so hard, sometimes.
>>
>> Meanwhile, we have a commit that broke some hardware. What do you want
>> to do about it? I agree with Aaron, things might need to be tweaked,
>> but ...
>> who's got that old hardware, and the time to do it? Do you have a
>> board of that ilk and the time to figure it out?
>>
>> How do you intend to resolve the problem caused by this commit?
>
>
> The process of deciding if i945 needs a fix has begun.
>
> As you may notice, the first thing was to try to find out if the original
> statement is reliable, backuped up by any documentation, or if the statement
> was made based on runs on some particular platform.
>
> So far no data from current and known codebase builds supports the statement
> that some PCI devices would not be accessible over MMCONF on platform with
> i945-
>
> From a fairly recent codebase we see PCI MMCONF setup for i945 had two flaws
> in design: a) There are PCI configuration access before MMCONF is enabled
> which need to be forced to use IO and b) With MMCONF_SUPPORT_DEFAULT, PCI
> configuration access in early ramstage would use IO instead and fail to
> access registers in range 0x100-0xfff. There is reason to believe i945
> development platform had same problems, which questions the reliability of
> the made conclusions.
>
>
> Kyösti
>