[Skiboot] [PATCH] pci: Add -Tn to SAS adapter's loc-code

[Brian King]

On 03/02/2017 09:51 PM, Ananth N Mavinakayanahalli wrote:
> On Fri, Mar 03, 2017 at 02:19:23PM +1100, Gavin Shan wrote:
>> On Fri, Mar 03, 2017 at 07:50:52AM +0530, Ananth N Mavinakayanahalli wrote:
>>> On Fri, Mar 03, 2017 at 10:54:42AM +1100, Gavin Shan wrote:
>>>> This adds -Tn to the device-tree node's loc-code property for SAS
>>>> adaptr as we did for ethernet adapter in commit 6558adff01bb ("
>>>> Add -Tn to ibm,loc-code for ethernet adaptors"). "n" represents
>>>> the function number of the PCI device.
>>>
>>> This would mean that the "n" would not necessarily be contiguous or
>>> start from 0 -- like what phyp does. Is that OK?
>>>
>>
>> It's not changed by the patch. If it's not correct, what we expect
>> from here?
> 
> Brian King would be right person to guide us here...

This is the algorithm that PHYP uses with PowerVM:

****************
This description applies to plug-in adapters.  Location codes for integrated devices include data we get from PHYP.


- PFW code keeps track of the base location code (i.e. up to the -C label) on a slot basis.
- For each PCI function associated with the slot, a location code is generated up to the -C label.
- If the function PCI class is not one of (PCI-host-bridge or PCI-PCI-bridge or USB or flash-memory or non-volatile-memory), append a -T label
-- If the location code base does not match the saved location code base
    then save the new location code base and start port numbering with 1; append port number 1
-- If the location code does match the saved location code base
   then increment the port number and append the port number

****************
To which Daniel then replied:
****************
Hi Carolyn,

Thanks for that explanation.

It's quite different to how functions are currently numbered in Skiboot.

 For each device probed:
 - copy the slot location code
 - if it is an ethernet device, add a '-Tn', where n is PCI function number + 1.

As you can see, labelling functions is stateless.

Probing is parallelised per PHB, but it looks like each PHB is done with a regular recursive probe, so we should be able to implement a PowerVM/PHYP style stateful model if necessary. Let's see how the rest of the root cause process goes.

****************

I don't see how we can use the PCI function number here, since these ports don't show up as separate functions but rather separate devices behind a PCI switch on the adapter. From the bugzilla, here is the lspci output:

# lspci | grep SAS
0001:05:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
0001:0b:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
0001:0c:00.0 RAID bus controller: IBM PCI-E IPR SAS Adapter (ASIC) (rev 02)
0005:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
0005:09:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
0006:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)
0006:09:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)


-Brian


-- 
Brian King
Power Linux I/O
IBM Linux Technology Center