[Skiboot] [PATCH v2] PHB3: Add M64 BAR count as a device node property

Gavin Shan gwshan at linux.vnet.ibm.com
Mon Oct 26 15:05:49 AEDT 2015

On Mon, Oct 26, 2015 at 02:36:53PM +1100, Stewart Smith wrote:
>Wei Yang <weiyang at linux.vnet.ibm.com> writes:
>> PHB3 has 16 M64 BARs, which will be used in host to map 64bit MMIO range.
>> This is more reasonable for host to retrieve this value than just use a
>> hard coded value.
>> This patch adds this property in device node, so that host could get it
>> from platform.
>> Signed-off-by: Wei Yang <weiyang at linux.vnet.ibm.com>
>As mentioned on IRC:
>- I think this needs to be documented in doc/device-tree that if
>  property doesn't exist, assume 16.
>  (yes, PCI binding documentation is kind of sparse, not even a pointer
>  to anywhere where it may be documented)
>- would be good to have ack from gavin or benh on this.

Exactly, the newly added properties are worthy to be documented well.
I agree it's a good idea to hide HW implementation in skiboot, but I
don't think this patch is complete from itself.

- P7IOC needs similar thing.
- More HW limitations would be exposed: single/shared modes, number of
  segments each M64 BAR can supports and total segment count. All those
  information is worthy to be carried in extendible way.

IO and M32 BAR has similar issues to be addressed.


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