[PATCH] powerpc/pci: Only do fixed PHB numbering on powernv

Guilherme G. Piccoli gpiccoli at linux.vnet.ibm.com
Tue Aug 9 21:19:33 AEST 2016

On 08/09/2016 01:44 AM, Michael Ellerman wrote:
> "Guilherme G. Piccoli" <gpiccoli at linux.vnet.ibm.com> writes:
>> On 08/08/2016 09:32 PM, Michael Ellerman wrote:
>>> "Guilherme G. Piccoli" <gpiccoli at linux.vnet.ibm.com> writes:
>>>> (i) What is the specific issue? Do you have some logs or at least a
>>>> "high-level" description of the problem in Xorg? I took a look in its
>>>> code and PCI domain is coded as u16, which is correct/expected. So it
>>>> seems a subtle bug we should investigate and hopefully fix.
>>> It was reported here:
>>>     https://lists.ozlabs.org/pipermail/linuxppc-dev/2016-August/147062.html
>>> It seems xorg just has a hard coded limit of 256 domains.
>> Thanks for the link Michael. I guess Xorg _had_ this limit in the
>> "past", since the function that was logged on error - xf86MapLegacyIO()
>> - was removed by a commit of 2014:
>> https://lists.x.org/archives/xorg-devel/2014-July/043224.html
> Aha, nice work.
> In fact it seems to be better than that, the array of domains was
> removed in 2011 in:
>    https://cgit.freedesktop.org/xorg/xserver/commit/?id=858fbbb40d7c69540cd1fb5315cebf811c6e7b3f
> Which is officially ancient history as far as I'm concerned.

Heheh great, good finding Michael!

>>>> (ii) Why is it related to the absence of pseries check?! You said this
>>>> was your bad, but as far as I understand, Xorg runs in pSeries too so
>>>> the issue should also be there heheh
>>> Well yes I guess it would, if anyone had tested Xorg on pseries :)
>> We use to test Xorg on pSeries regularly; in fact, I made a quick test
>> today:
>> http://imgur.com/a/l1lP8
>> I forced the domain to be 0xffff as in the above image, and everything
>> worked fine.
> Awesome.
>>> I think for now I'm going to apply this, and we'll work out something
>>> else later.
>> OK, I guess your solution is fine and solves the pasemi issue quickly,
> No given the above info on xorg I'll drop this, and merge just the
> endian fix.

Perfect, thanks!

> cheers

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