[PATCH v9 00/10] PCI: dwc: ep: Fix DBI access failure for drivers requiring refclk from host

[Manivannan Sadhasivam]

Hello,

This series is the continuation of previous work by Vidya Sagar [1] to fix the
issues related to accessing DBI register space before completing the core
initialization in some EP platforms like Tegra194/234 and Qcom EP.

Since Vidya is busy, I took over the series based on his consent (off-list
discussion).

NOTE
====

Based on the comments received in v7 [2], I've heavily modified the series
to fix several other issues reported by Bjorn and Niklas. One noticeable
change is getting rid of the 'core_init_notifer' flag added to differentiate
between glue drivers requiring refclk from host and drivers getting refclk
locally.

By getting rid of this flag, now both the DWC EP driver and the EPF drivers
can use a single flow and need not distinguish between the glue drivers.

We can also get rid of the 'link_up_notifier' flag in the future by following
the same convention.

Testing
=======

I've tested the series on Qcom SM8450 based dev board that depends on refclk
from host with EPF_MHI driver. It'd be good to test this series on platforms
that generate refclk locally and also with EPF_TEST driver.

- Mani

[1] https://lore.kernel.org/linux-pci/20221013175712.7539-1-vidyas@nvidia.com/
[2] https://lore.kernel.org/linux-pci/20231120084014.108274-1-manivannan.sadhasivam@linaro.org/

Changes in v9:
- Incorporated changes for missing drivers (Niklas)
- Reworded the dw_pcie_ep_cleanup() API kdoc (Niklas)
- Reworded the description of patch 6/10 (Frank)
- Collected reviews
- Link to v8: https://lore.kernel.org/r/20240224-pci-dbi-rework-v8-0-64c7fd0cfe64@linaro.org

Changes in v8:

- Rebased on top of v6.8-rc1
- Removed the deinit callback from struct dw_pcie_ep_ops
- Renamed dw_pcie_ep_exit() to dw_pcie_ep_deinit()
- Introduced dw_pcie_ep_cleanup() API for drivers supporting PERST#
- Renamed dw_pcie_ep_init_complete() to dw_pcie_ep_init_registers()
- Called dw_pcie_ep_init_registers() API directly from all glue drivers
- Removed "core_init_notifier" flag
- Added a generic dw_pcie_ep_linkdown() API to handle LINK_DOWN event and used
  it in qcom driver
- Added Kernel-doc comments for DWC EP APIs

Changes in v7:

- Rebased on top of v6.7-rc1
- Kept the current dw_pcie_ep_init_complete() API instead of renaming it to
  dw_pcie_ep_init_late(), since changing the name causes a slight ambiguity.
- Splitted the change that moves pci_epc_init_notify() inside
  dw_pcie_ep_init_notify() to help bisecting and also to avoid build issue.
- Added a new patch that moves pci_epc_init_notify() inside
  dw_pcie_ep_init_notify().
- Took over the authorship and dropped the previous Ack as the patches are
  heavily modified.

Changes in v6:

- Rebased on top of pci/next (6e2fca71e187)
- removed ep_init_late() callback as it is no longer necessary

For previous changelog, please refer [1].

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
---
Manivannan Sadhasivam (10):
      PCI: dwc: ep: Remove deinit() callback from struct dw_pcie_ep_ops
      PCI: dwc: ep: Rename dw_pcie_ep_exit() to dw_pcie_ep_deinit()
      PCI: dwc: ep: Introduce dw_pcie_ep_cleanup() API for drivers supporting PERST#
      PCI: dwc: ep: Fix DBI access failure for drivers requiring refclk from host
      PCI: dwc: ep: Rename dw_pcie_ep_init_complete() to dw_pcie_ep_init_registers()
      PCI: dwc: ep: Call dw_pcie_ep_init_registers() API directly from all glue drivers
      PCI: dwc: ep: Remove "core_init_notifier" flag
      PCI: dwc: ep: Add a generic dw_pcie_ep_linkdown() API to handle LINK_DOWN event
      PCI: qcom-ep: Use the generic dw_pcie_ep_linkdown() API to handle LINK_DOWN event
      PCI: dwc: ep: Add Kernel-doc comments for APIs

 drivers/pci/controller/dwc/pci-dra7xx.c           |   9 +
 drivers/pci/controller/dwc/pci-imx6.c             |  10 +
 drivers/pci/controller/dwc/pci-keystone.c         |  11 +
 drivers/pci/controller/dwc/pci-layerscape-ep.c    |   9 +
 drivers/pci/controller/dwc/pcie-artpec6.c         |  15 +-
 drivers/pci/controller/dwc/pcie-designware-ep.c   | 309 +++++++++++++++-------
 drivers/pci/controller/dwc/pcie-designware-plat.c |  11 +
 drivers/pci/controller/dwc/pcie-designware.h      |  19 +-
 drivers/pci/controller/dwc/pcie-keembay.c         |  18 +-
 drivers/pci/controller/dwc/pcie-qcom-ep.c         |   6 +-
 drivers/pci/controller/dwc/pcie-rcar-gen4.c       |  28 +-
 drivers/pci/controller/dwc/pcie-tegra194.c        |   5 +-
 drivers/pci/controller/dwc/pcie-uniphier-ep.c     |  15 +-
 drivers/pci/endpoint/functions/pci-epf-test.c     |  18 +-
 include/linux/pci-epc.h                           |   3 -
 15 files changed, 354 insertions(+), 132 deletions(-)
---
base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d
change-id: 20240224-pci-dbi-rework-b2e99a62930c

Best regards,
-- 
Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>