Hello,
> This patch adds support for OPP to vote for the performance state of RPMH
> power domain based upon PCIe speed it got enumerated.
>
> QCOM Resource Power Manager-hardened (RPMh) is a hardware block which
> maintains hardware state of a regulator by performing max aggregation of
> the requests made by all of the processors.
>
> PCIe controller can operate on different RPMh performance state of power
> domain based up on the speed of the link. And this performance state varies
> from target to target.
>
> It is manadate to scale the performance state based up on the PCIe speed
> link operates so that SoC can run under optimum power conditions.
>
> Add Operating Performance Points(OPP) support to vote for RPMh state based
> upon GEN speed link is operating.
>
> Before link up PCIe driver will vote for the maximum performance state.
>
> As now we are adding ICC BW vote in OPP, the ICC BW voting depends both
> GEN speed and link width using opp-level to indicate the opp entry table
> will be difficult.
>
> In PCIe certain gen speeds like 2.5GT/s x2 & 5.0 GT/s X1 or 8.0 GT/s x2 &
> 16GT/s x1 use same ICC bw if we use freq in the OPP table to represent the
> PCIe speed number of PCIe entries can reduced.
>
> So going back to use freq in the OPP table instead of level.
>
> To access PCIe registers of the host controller and endpoint PCIe
> BAR space, config space the CPU-PCIe ICC (interconnect) path should
> be voted otherwise it may lead to NoC (Network on chip) timeout.
> We are surviving because of other driver voting for this path.
>
> As there is less access on this path compared to PCIe to mem path
> add minimum vote i.e 1KBps bandwidth always which is sufficient enough
> to keep the path active and is recommended by HW team.
>
> In suspend to ram case there can be some DBI access. Except in suspend
> to ram case disable CPU-PCIe ICC path after register space access
> is done.
Applied to controller/qcom, thank you!
[01/03] PCI: qcom: Add ICC bandwidth vote for CPU to PCIe path
https://git.kernel.org/pci/pci/c/18f331d9c6db
[02/03] PCI: Bring the PCIe speed to MBps logic to new pcie_dev_speed_mbps()
https://git.kernel.org/pci/pci/c/4bf3029dc2a1
[03/03] PCI: qcom: Add OPP support to scale performance
https://git.kernel.org/pci/pci/c/78b5f6f8855e
Krzysztof
