Re: [PATCH v4 1/3] PCI: pciehp: Add support for disabling in-band presence

From: Stuart Hayes
Date: Tue Dec 31 2019 - 17:07:24 EST




On 11/26/19 8:19 PM, Stuart Hayes wrote:
> On Tue, Nov 26, 2019 at 7:36 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>>
>> On Fri, Oct 25, 2019 at 03:00:45PM -0400, Stuart Hayes wrote:
>>> From: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
>>>
>>> The presence detect state (PDS) is normally a logical or of in-band and
>>> out-of-band presence. As of PCIe 4.0, there is the option to disable
>>> in-band presence so that the PDS bit always reflects the state of the
>>> out-of-band presence.
>>>
>>> The recommendation of the PCIe spec is to disable in-band presence
>>> whenever supported.
>>
>> I think I'm fine with this patch, but I would like to include the
>> specific reference for this recommendation. If you have it handy, I
>> can just insert it.
>>
>
> The PCI Express Base Specification Revision 5.0, Version 1.0, in the
> implementation note under Appendix I ("Async Hot-Plug Reference
> Model"), it says "If OOB PD is being used and the associated DSP
> supports In-Band PD Disable, it is recommended that the In-Band PD
> Disable bit be Set, ..."
>
>

Is that what you were looking for? Please let me know if there's anything
else I can do to help.