Re: [RFC 13/20] drm/i915/dp: Extract drm_dp_downstream_read_info()

[Imre Deak]

On Fri, Aug 21, 2020 at 01:43:39PM -0400, Lyude Paul wrote:
> [...] 
> > The wording is a bit unclear, but as I understand the Standard only
> > calls for the above:
> > 
> > """
> > A DP upstream device shall read the capability from DPCD Addresses 00080h
> > through 00083h. A DP Branch device with multiple DFPs shall report the
> > detailed
> > capability information of the lowest DFP number to which a downstream device
> > is connected, consistent with the DisplayID or legacy EDID access routing
> > policy
> > of an SST-only DP Branch device as described in Section 2.1.4.1.
> > """
> 
> So-I saw this too, but notice the use of the language "A /DP Branch/ device with
> multiple DFPs shall report the detailed…". This makes me think it's implying
> that this is a requirement for MSTBs and not SST sinks, just a guess.

Not sure either. The above could also refer to an SST branch device with
multiple DFPs (for instance a DP Replicator branch device).

--Imre