Re: [PATCH] arm64: dts: qcom: qcs6490-rb3gen2: Add PCIe nodes

[Dmitry Baryshkov]

On Sat, Oct 12, 2024 at 06:13:34PM +0530, Manivannan Sadhasivam wrote:
> On Fri, Oct 11, 2024 at 05:24:29PM +0530, Krishna Chaitanya Chundru wrote:
> 
> [...]
> 
> > > > The logic here is that the fixed endpoints in the switch will get an unique SID
> > > > and the devices getting attached to slots will share the same SID of the bus
> > > > (this is the usual case with all Qcom SoCs).
> > > > 
> > > > But I guess we would need 'iommu-map-mask' as well. Hope this addresses your
> > > > concern.
> > > 
> > > Yes, thank you!
> > > 
> > Hi dimitry & mani,
> > 
> > This particular board variant doesn't expose any open slots to connect
> > a different endpoints like another switch(which might have BDF unknown
> > to us) so static table should be fine for this board variant.
> > 
> > I tries to add iommu-map-mask property, the issue with that property is
> > that the driver is applying the mask to the bdf before searching for the
> > entry in the table. If I use a mask value which satisfies all the
> > entries in the table ( mask as 0x718) and if a new bdf is enumerated
> > lets say 0x600 due to mask 0x718 its value is again 0x600 only.
> > 
> > Can we skip iommu-map-mask property and use only static table for this
> > board as we know this board doesn't expose any open slots.
> > 
> 
> Hmm, I was not aware that it doesn't have open slots. Fine with me then.

It doesn't feature open slots, but it has two PCIe connections on HS2 /
HS3. Users might attach external PCIe devices.

Krishna, could you please clarify, how those two connections are routed?

-- 
With best wishes
Dmitry