[Skiboot] nvlink2 topology

Alexey Kardashevskiy aik at ozlabs.ru
Thu Jul 26 12:56:20 AEST 2018

On 26/07/2018 03:53, Reza Arbab wrote:
> On Tue, Jul 24, 2018 at 12:12:43AM +1000, Alexey Kardashevskiy wrote:
>> But before I try this, the existing tree seems to have a problem at
>> (same with another xscom node):
>> /sys/firmware/devicetree/base/xscom at 603fc00000000/npu at 5011000
>> ./link at 4/ibm,slot-label
>>                 "GPU2"
>> ./link at 2/ibm,slot-label
>>                 "GPU1"
>> ./link at 0/ibm,slot-label
>>                 "GPU0"
>> ./link at 5/ibm,slot-label
>>                 "GPU2"
>> ./link at 3/ibm,slot-label
>>                 "GPU1"
>> ./link at 1/ibm,slot-label
>>                 "GPU0"
>> This comes from hostboot.
>> Witherspoon_Design_Workbook_v1.7_19June2018.pdf on page 39 suggests that
>> link at 3 and link at 5 should be swapped. Which one is correct?
> I would think link at 3 should be "GPU2" and link at 5 should be "GPU1".
> If so, it's a little surprising that this hasn't broken anything. The
> driver has its own way of discovering what connects to what, so maybe
> there really just isn't a consumer of these labels yet.

Can you please 1) make sure we do understand things right and these are
not some weird muxes somewhere between GPU and P9 2) fix it? Thanks :)


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