[PATCH v6 0/6] PCI: qcom: Add support for OPP

[Krishna chaitanya chundru <quic_krichai@quicinc.com>]

This patch adds support for OPP to vote for the performance state of RPMH
power domain based upon GEN speed it PCIe 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 GEN1x2 & GEN2X1 or GEN3x2 & GEN4x1 use
same icc bw if we use freq in the opp table to represent the PCIe Gen
speed number of PCIe entries can reduced.

So going back to use freq in the opp table instead of level.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
Changes frm v5:
	- Add ICC BW voting as part of OPP, rebase the latest kernel, and only
	- either OPP or ICC BW voting will supported we removed the patch to
	- return eror for icc opp update patch.
	- As we added the icc bw voting in opp table I am not including reviewed
	- by tags given in previous patch.
	- Use opp freq to find opp entries as now we need to include pcie link
	- also in to considerations.
	- Add CPU-PCIe BW voting which is not present till now.
	- Drop  PCI: qcom: Return error from 'qcom_pcie_icc_update' as either opp or icc bw
	- only one executes and there is no need to fail if opp or icc update fails.
	- Link for v5: https://lore.kernel.org/linux-arm-msm/20231101063323.GH2897@thinkpad/T/
Changes from v4:
	- Added a separate patch for returning error from the qcom_pcie_upadate
	  and moved opp update logic to icc_update and used a bool variable to 
	  update the opp.
	- Addressed comments made by pavan.
changes from v3:
	- Removing the opp vote on suspend when the link is not up and link is not
	  up and add debug prints as suggested by pavan.
	- Added dev_pm_opp_find_level_floor API to find the highest opp to vote.
changes from v2:
	- Instead of using the freq based opp search use level based as suggested
	  by Dmitry Baryshkov.
Changes from v1:
        - Addressed comments from Krzysztof Kozlowski.
        - Added the rpmhpd_opp_xxx phandle as suggested by pavan.
        - Added dev_pm_opp_set_opp API call which was missed on previous patch.

---
Krishna chaitanya chundru (6):
      dt-bindings: PCI: qcom: Add interconnects path as required property
      arm64: dts: qcom: sm8450: Add interconnect path to PCIe node
      PCI: qcom: Add missing icc bandwidth vote for cpu to PCIe path
      dt-bindings: pci: qcom: Add opp table
      arm64: dts: qcom: sm8450: Add opp table support to PCIe
      PCI: qcom: Add OPP support to scale performance state of power domain

 .../devicetree/bindings/pci/qcom,pcie.yaml         |   6 ++
 arch/arm64/boot/dts/qcom/sm8450.dtsi               |  82 +++++++++++++++
 drivers/pci/controller/dwc/pcie-qcom.c             | 114 ++++++++++++++++++---
 3 files changed, 187 insertions(+), 15 deletions(-)
---
base-commit: 70d201a40823acba23899342d62bc2644051ad2e
change-id: 20240112-opp_support-3a1839c6a171

Best regards,
-- 
Krishna chaitanya chundru <quic_krichai@quicinc.com>